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Evaluation of facial expression in acute pain in cats

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... In the last decade, a number of other species have had facial expression scales developed and validated to varying degrees as a pain assessment tool (Dalla Costa et al., 2014;Di Giminiani et al., 2016;Gleerup et al., 2015;Guesgen et al., 2016;Häger et al., 2017;Holden et al., 2014;Keating et al., 2012;MacRae et al., 2018;McLennan et al., 2016;Reijgwart et al., 2017;Sotocinal et al., 2011;van Loon and VanDierendonck, 2015). For this technique of pain assessment to be effective, we must understand the challenges and limitations to the development and use of facial expression as a pain assessment method. ...
... Within the last twelve years a number of facial expression scales (also known as "Grimace Scales") have been designed specifically to assess pain in animals. Many of these scales focus on just four or five facial areas and consider a particular action as present (score 2), partially present (score 1) or not present (score 0) (Dalla Costa et al., 2014;Di Giminiani et al., 2016;Gleerup et al., 2015;Guesgen et al., 2016;Häger et al., 2017;Holden et al., 2014;Keating et al., 2012;Langford et al., 2010;McLennan et al., 2016;Reijgwart et al., 2017;Sotocinal et al., 2011;van Loon and VanDierendonck, 2015). Animals were tested in pain and non-pain states, and a comparison made of their facial expression scores in each context. ...
... These factors include the experimental design, the pain stimulus used, provision of analgesia, and another known pain assessment tool for comparison, as a minimum. The following scales are now considered: the Mouse Grimace Scale (MGS) (Langford et al., 2010), the Rat Grimace Scale (RGS) (Sotocinal et al., 2011), the Rabbit Grimace Scale (RbtGS) (Keating et al., 2012), the Ferret Grimace Scale (FGS) (Reijgwart et al., 2017) (Guesgen et al., 2016), the Piglet Grimace Scale (PGS) (Di Giminiani et al., 2016) and the facial pain assessment tool for cats developed by Holden et al. (2014). ...
Article
Effective management of pain is critical to the improvement of animal welfare. For this to happen, pain must be recognised and assessed in a variety of contexts. Pain is a complex phenomenon, making reliable, valid, and feasible measurement challenging. The use of facial expressions as a technique to assess pain in non-verbal human patients has been widely utilised for many years. More recently this technique has been developed for use in a number of non-human species: rodents, rabbits, ferrets, cats, sheep, pigs and horses. Facial expression scoring has been demonstrated to provide an effective means of identifying animal pain and in assessing its severity, overcoming some of the limitations of other measures for pain assessment in animals. However, there remain limitations and challenges to the use of facial expression as a welfare assessment tool which must be investigated. This paper reviews current facial expression pain scales (“Grimace Scales"), discussing the general conceptual and methodological issues faced when assessing pain, and highlighting the advantages of using facial expression scales over other pain assessment methods. We provide guidance on how facial expression scales should be developed so as to be valid and reliable, but we also provide guidance on how they should be used in clinical practice.
... 15,16 The Glasgow Composite Measure Pain Scale (CMPS-Feline) has recently been validated for cats and incorporates evaluation of the patient's facial expression, decreasing the misclassification of painful vs nonpainful cats compared with the earlier version of the tool, which lacked the embedded facial scale. [17][18][19] The development of pain assessment tools for use in feline patients is of utmost importance, and further work in this area is still greatly needed. ...
... This reliability is lower than that obtained with the Botucatu-MCPS, which was good to very good among blinded observers as assessed by video recordings. 15 No information could be found regarding inter-rater reliability for the CMPS-Feline, which has been validated recently, [17][18][19] precluding comparison with the current results using the CSU-FAPS. Compared with the more detailed Botucatu-MCPS, the CSU-FAPS is a simpler and more concise tool, which may make it more apt for use in clinical practice. ...
... 15 No information could be found regarding influence of training level on reliability in the recently validated CMPS-Feline. [17][18][19] One possible explanation as to why training level might influence the performance of a pain assessment tool is that the rater's knowledge base and experience might compensate for gaps in the tool. Indeed, education on pain management in the veterinary curriculum and continuing education to veterinarians remains an unmet need. ...
Article
Objectives: The objective of this study was to determine the inter-rater reliability and convergent validity of the Colorado State University Feline Acute Pain Scale (CSU-FAPS) in a preliminary appraisal of its performance in a clinical teaching setting. Methods: Sixty-eight female cats were assessed for pain after ovariohysterectomy. A cohort of 21 cats was examined independently by four raters (two board-certified anesthesiologists and two anesthesia residents) with the CSU-FAPS, and intra-class correlation coefficient (ICC) was used to determine inter-rater reliability. Weighted Cohen's kappa was used to determine inter-rater reliability centered on the 'need to reassess analgesic plan' (dichotomous scale). A separate cohort of 47 cats was evaluated independently by two raters (one board-certified anesthesiologist and one veterinary small animal rotating intern) using the CSU-FAPS and the Glasgow Composite Measure Pain Scale (CMPS-Feline), and Spearman rank-order correlation was determined to assess convergent validity. Reliability was interpreted using Altman's classification as very good, good, moderate, fair and poor. Validity was considered adequate if correlation coefficients were between 0.4 and 0.8. Results: The ICC was 0.61 for anesthesiologists and 0.67 for residents, indicating good reliability. Weighted Cohen's kappa was 0.79 for anesthesiologists and 0.44 for residents, indicating moderate to good reliability. The Spearman rank correlation indicated a statistically significant ( P = 0.0003) positive correlation (0.31; 95% confidence interval 0.14-0.46) between the CSU-FAPS and the CMPS-Feline. Conclusions and relevance: The CSU-FAPS showed moderate-to-good inter-rater reliability when used by veterinarians to assess pain level or need to reassess analgesic plan after ovariohysterectomy in cats. The validity fell short of current guidelines for correlation coefficients and further refinement and testing are warranted to improve its performance.
... Domestic Short Haired cats were identified as those that had mesocephalic type features (see further) and did not display any distinct visual features that could enable then to be classified as any other recognized breed type. Knowledge of the cat Facial Action Coding System and the reference manual was used by LF (a certified reliable catFACS coder) to determine neutrality of expressions within the images [see (41)], with the aim to discount any cats displaying various muscle contractions or other expressions associated with affective states such as pain, fear or frustration [e.g., (45,(49)(50)(51)]. As these images were from unknown populations, no information relating to their geographical location, age, sex, neuter or health status was available, although images of kittens, cats with proportionately large jowls (as seen in some adult unneutered males) and cats which looked physically ill or in distress or were not included. ...
... The implications of these findings are potentially relevant not only to the domestic cat (50,51), but other species where standard visual tools (i.e., grimace scales) are used to identify pain via the face. These scales are generally developed and validated using small and/or homogenous populations [e.g., (60)(61)(62)], of which many display variation in their facial morphology at a species level [e.g., (63)], including exaggerated features such as paedomorphy [e.g., (8,18)]. ...
... Furthermore, in contrast to dogs, cat adoption does not appear to be contingent upon their facial expressions, only their overt communicative gestures such as rubbing (42). However, the fact that clear and differentiable facial expressions have previously been linked with different affective states (49) including pain (45,50,51) in this species, as well as the morphologically similar Scottish wild cat (75), suggests that their facial expressions do have communicative value. Whilst it is likely that overt pain expression would have been strongly selected against in cat's ancestors, this is less likely to have extended to their facial expressions, because they are not easily detected at a distance, and would confer distinct advantages in the form of care solicitation during the neonatal period. ...
Article
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During their domestication via artificial selection, humans have substantially modified the morphology and thus visual appearance of non-human animals. While research highlights the negative impact of these modifications on physical functioning, little is known about their impact on behavior and signaling, either toward humans or conspecifics. Changes in the appearance of the face, such as those associated with, but not limited to, facial expressions, form an important part of non-verbal communication. In companion animals, the face is one of their most visually diverse features (due to human-driven selection), which may impact the visual clarity of expressions and other forms of signaling. Using the domestic cat as our model, we applied a new analytical technique in order to understand the impact of breed variation on relative positioning of facial landmarks, chosen specifically for their association with the production of various facial movements, and the expression of affect. We then assessed the extent to which facial appearances known to be associated with a specific underlying state (i.e., pain, assessed via a validated, facial pain score), could be reliably detected in a morphologically diverse population. Substantial baseline variation in landmarks was identified at both the cephalic (e.g., brachycephalic, dolichocephalic, mesocephalic) as well as breed levels. While differences in facial pain scores could successfully differentiate between “pain” and “no pain” in the facial appearance of domestic shorthaired cats (DSH), these differences were no longer detectable when assessed within a larger more morphologically diverse population, after corrections for multiple testing were applied. There was also considerable overlap between pain scores in the DSH “pain” population and the neutral faces of other breeds. Additionally, for several paedomorphic breeds, their neutral face shapes produced scores indicative of greater pain, compared to most other breeds, including the DSH cats actually in pain. Our findings highlight the degree to which anthropocentric selection might disrupt the communicative content of animals' faces, in this case the domestic cat. These results also suggest a potential human preference for features extending beyond the infantile, to include negatively-valenced facial forms such as pain.
... In cats, methods to quantify facial changes, focusing on linear distances between specific facial landmarks (i.e. distances between ears and muzzle) allowed distinction between painful and pain-free animals 25 . However, orbital tightening and whiskers position, that are commonly listed as action units in other species, were not included and a grimace scale for assessing pain in cats using facial expressions has not been published. ...
... The medial ear angle increases and the lateral decreases as the ears flattens in painful cats. Distances between two pairs of landmarks in the cats' ears and muzzle were previously reported as significantly different between painful and pain-free cats 25 . ...
... Animals were free-ranging and able to express their natural behaviours. Other studies included photographs taken when the animals were restrained 19,22,24,25 . However, physical restraint significantly affected facial expressions scores in lambs 21 . ...
Article
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Grimace scales have been used for pain assessment in different species. This study aimed to develop and validate the Feline Grimace Scale (FGS) to detect naturally-occurring acute pain. Thirty-five client-owned and twenty control cats were video-recorded undisturbed in their cages in a prospective, case-control study. painful cats received analgesic treatment and videos were repeated one hour later. five action units (AU) were identified: ear position, orbital tightening, muzzle tension, whiskers change and head position. Four observers independently scored (0-2 for each AU) 110 images of control and painful cats. the FGS scores were higher in painful than in control cats; a very strong correlation with another validated instrument for pain assessment in cats was observed (rho = 0.86, p < 0.001) as well as good overall inter-rater reliability [icc = 0.89 (95% CI: 0.85-0.92)], excellent intra-rater reliability (ICC > 0.91), and excellent internal consistency (Cronbach's alpha = 0.89). The FGS detected response to analgesic treatment (scores after analgesia were lower than before) and a cutoff score was determined (total pain score > 0.39 out of 1.0). The FGS is a valid and reliable tool for acute pain assessment in cats.
... Three investigated vocalisations, showing that people have limited abilities to correctly match recorded 'meows' to the contexts or states of unfamiliar cats (though some raters are successful, especially for familiar cats) (Nicastro & Owren 2003;Belin et al 2008; Ellis et al 2015; Table S1 [https://www.ufaw.org.uk/the-ufaw-journal/supplementarymaterial]). The fourth focused on facial expressions (Holden et al 2014): Veterinarians and veterinary nurses asked to distinguish between still images of the faces of painful and pain-free cats were often incorrect. However, significantly high success rates were observed for some images and, also, again, for some individual raters. ...
... However, significantly high success rates were observed for some images and, also, again, for some individual raters. Furthermore, careful quantitative measurements of specific anatomical landmarks revealed that pain did indeed induce consistent, if small, changes in cats' muzzle shapes and ear positions (Holden et al 2014). Evidence thus indicates that at least some humans can detect subtle changes in painful cats' faces, but whether such abilities translate across a wider spectrum of emotions has ...
... We also sought to determine whether such abilities extend to positive states. As well as testing these hypotheses, we also aimed to identify how various rater characteristics, such as gender and experience with cats, influence raters' abilities to identify feline affective states: such factors often prove important in similar research on dogs ( Wan et al 2012;Schirmer et al 2013;Flint et al 2018), and the few cat studies to date already suggest large individual differences between people (Nicastro & Owren 2003;Holden et al 2014). ...
Article
Although cats' popularity as pets rivals that of dogs, cats are little studied, and people's abilities to read this apparently 'inscrutable' species have attracted negligible research. To determine whether people can identify feline emotions from cats' faces, participants (n = 6,329) each viewed 20 video clips of cats in carefully operationalised positively (n = 10) or negatively valenced states (n = 10) (cross-factored with low and high activity levels). Obvious cues (eg open mouths or fully retracted ears) were eliminated. Participants' average scores were low (11.85/20 correct), but overall above chance; furthermore, 13% of participants were individually significantly successful at identifying the valence of cats' states (scoring ≥ 15/20 correct). Women were more successful at this task than men, and younger participants more successful than older, as were participants with professional feline (eg veterinary) experience. In contrast, personal contact with cats (eg pet-owning) had little effect. Cats in positive states were most likely to be correctly identified, particularly if active rather than inactive. People can thus infer cats' affective states from subtle aspects of their facial expressions (although most find this challenging); and some individuals are very good at doing so. Understanding where such abilities come from, and precisely how cats' expressions change with affective state, could potentially help pet owners, animal care staff and veterinarians optimise feline care and welfare.
... In humans, the reliable differentiation of fear and surprise, and their perceived intensity, is limited when facial images are coded statically rather than dynamically 26 (cited in 25 ). This highlights another potential limitation of relying on static scales such as photographs 4,8,13,14 and illustrations [9][10][11] to visually identify the presence or absence of certain expressions in non-human animals. Additionally, the FACS approach does not readily support the reliable capturing or quantification of the intensity within an expression. ...
... Another approach has applied 'traditional' morphometric methods to quantify facial changes, focusing on linear distances between specific facial landmarks across 'pain' and 'no pain' conditions (e.g. 10 ). 'Cartoon-like' hand-drawn images of cat facial expressions were then produced as a means of visualising statistically significant outputs. ...
... If such factors are not sufficiently addressed (e.g. 10,11 ), then the results are not necessarily robust or reliable. ...
Article
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Facial expression is a common channel for the communication of emotion. However, in the case of non-human animals, the analytical methods used to quantify facial expressions can be subjective, relying heavily on extrapolation from human-based systems. Here, we demonstrate how geometric morphometrics can be applied in order to overcome these problems. We used this approach to identify and quantify changes in facial shape associated with pain in a non-human animal species. Our method accommodates individual variability, species-specific facial anatomy, and postural effects. Facial images were captured at four different time points during ovariohysterectomy of domestic short haired cats (n = 29), with time points corresponding to varying intensities of pain. Images were annotated using landmarks specifically chosen for their relationship with underlying musculature, and relevance to cat-specific facial action units. Landmark data were subjected to normalisation before Principal Components (PCs) were extracted to identify key sources of facial shape variation, relative to pain intensity. A significant relationship between PC scores and a well-validated composite measure of post-operative pain in cats (UNESP-Botucatu MCPS tool) was evident, demonstrating good convergent validity between our geometric face model, and other metrics of pain detection. This study lays the foundation for the automatic, objective detection of emotional expressions in a range of non-human animal species.
... Since Langford et al 1 first reported on facial expressions associated with pain in mice, there has been growing interest in tools for assessment of facial expressions linked to pain in a range of non-human animal species. Such tools have been created and validated for various species, including rats 2 , rabbits 3 , horses 4 , pigs 5 , sheep 6 , ferrets 7 and cats 8 . Optimal pain management in cats presents various challenges due to a lack of well-established management strategies for certain painful conditions 9 , reservations about the adverse effects of analgesics 10 , uncertainty around the reliability and specificity of certain behavioural indicators of pain 11 and a limited ability of humans to accurately interpret facial expressions associated with negative affect in this species 12 . ...
... We define four regions of interest on cat faces: left eye region (defined by landmarks 4,5,6,7,8,37,38,39, with central point on the median of landmarks 37 and 38); right eye region (defined by landmarks 2,9,10,11,12,40,41,42 with central point on the median of landmarks 41 and 42); nose, mouth and whiskers region (defined by landmarks 1,3,13,14,15,16,17,18,19,20,21,22,33,34,35,36,43,44,45,46,47,48 Preprocessing pipeline. The first step is facial alignment, which centers the landmarks, and is performed as described in the previous section. ...
Article
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Facial expressions in non-human animals are closely linked to their internal affective states, with the majority of empirical work focusing on facial shape changes associated with pain. However, existing tools for facial expression analysis are prone to human subjectivity and bias, and in many cases also require special expertise and training. This paper presents the first comparative study of two different paths towards automatizing pain recognition in facial images of domestic short haired cats (n = 29), captured during ovariohysterectomy at different time points corresponding to varying intensities of pain. One approach is based on convolutional neural networks (ResNet50), while the other—on machine learning models based on geometric landmarks analysis inspired by species specific Facial Action Coding Systems (i.e. catFACS). Both types of approaches reach comparable accuracy of above 72%, indicating their potential usefulness as a basis for automating cat pain detection from images.
... Exemplos de sinais comportamentais a que devemos estar atentos são: Vocalização reduzida, diminuição da atividade e curiosidade, imobilidade (pode estar contraído/firme), adoção de posições anormais que refletem desconforto e proteção da área lesada, possível agressividade no ato de manipulação, diminuição do "grooming" geral (mas possível lambedura excessiva numa área restrita), diminuição do apetite, alterações nos padrões de sono, entre outros. (Holden et al. 2014) (Reid et al., 2018) (Merola and Mills, 2016;Mathews et al., 2014). ...
... Os sinais comportamentais a que devemos estar atentos no cão são: Vocalização aumentada, mutilação/"grooming" constante numa área, menor interação com o tutor, alterações no comportamento/personalidade (agitação ou depressão), postura corporal alterada (posição baixa, relutância a certos movimentos), perda de peso, entre outros. (Holden et al. 2014) (Reid et al., 2018) (Merola and Mills, 2016;Mathews et al., 2014). ...
... The majority of responders also reported that, at the time of participation, their country of residency had issued some level of social distancing measures (75%, N = 219), rather than complete lockdown (23%, N = 66) or no measures at all (2%, N = 6). The majority of responders also reported no or slight financial distress caused by the pandemic (81%, N = 236). ...
... We believe that cats' better physical QoL is an artefact caused by cats' subtle expression of physical discomfort. Evidence indicates that cats communicate their experience of pain mostly through facial expressions [65,66], hiding, and immobility [67], which may be difficult to interpret for pet owners. On the other hand, cats' lower scores of social QoL likely represents the owners' limited engagement in joint activities, such as training or exercise, and lack of interaction with the pet, as cat owners may be prone to believing that cats are selfregulated in terms of exercise and prefer solo over social play [68]. ...
Article
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The COVID-19 pandemic caused lifestyle changes, with unknown effect on pets’ quality of life (QoL). Between May and July 2020, we distributed an online survey to investigate the role of several factors on feline and canine QoL, including lockdown-related factors. We used existing scales to measure human and pets’ personalities (Reinforcement Sensitivity Theory Personality Questionnaire, RST-PQ; RST-Dog; RST-Cat) and the human–animal relationship (Lexington Attachment to Pets Scale, LAPS) and the Milan Pet Quality of Life instrument (MPQL). Overall, 235 participants reported about 242 adult pets (Ncats = 78, Ndogs = 164). Factor analysis confirmed the structure and internal reliability of the existing scales (RST-PQ, RST-Dog, RST-Cat, LAPS) and suggested a four-factor structure for the MPQL (physical, psychological, social, environmental). The results indicate that the pets’ psysical QoL was largely explained by pet-related elements (pets’ demographics and life experience, and pets’ personality). Conversely, the pets’ psychological QoL was explained mostly by owner-related elements, such as the owners’ demographics, COVID-19-related changes, and the owners’ personality. Predictably, the pets’ environmental QoL is mostly explained by environmental factors, such as the outdoor access in the home environment and the country. Finally, the pets’ social QoL was explained by the larger combination of models: pets’ characteristics and personality, environment and COVID-19-related changes, and the pet–human relationship. These findings can be explained by two non-mutually exclusive mechanisms. The reported changes may be a by-product of the COVID-19 pandemic’s psychological and lifestyle effects on the owners, which in turn alter the way the owners interact with their pets and look after them. However, the owners’ characteristics and mood may bias their answers regarding their pets.
... As mentioned by Häger et al. [11], conscious perception of pain is represented by a change in facial expressions, such as ears flattening and tension in the muscles of the nose, mouth, and the orbital region [28,29]. Identifying these changes has been proposed as an alternative to assess the degree of pain through grimace scales based on the facial expression of cats [30,31], pigs [13], mice [32], and rats [33]. ...
... In felines, the Feline Grimace Scale (FGS) has been implemented to identify acute pain using facial expressions, with an efficacy of up to 94% to differentiate between pain and pain-free cats. These scales have made it possible to identify that 85% of the facial changes observed during a painful event are concentrated in the ears, eyes, whiskers, and nose [30]. As previously mentioned, the movements of these regions serve as clinical assistance for the identification of pain. ...
Article
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Animals’ facial expressions are involuntary responses that serve to communicate the emotions that individuals feel. Due to their close co-existence with humans, broad attention has been given to identifying these expressions in certain species, especially dogs. This review aims to analyze and discuss the advances in identifying the facial expressions of domestic dogs and their clinical utility in recognizing pain as a method to improve daily practice and, in an accessible and effective way, assess the health outcome of dogs. This study focuses on aspects related to the anatomy and physiology of facial expressions in dogs, their emotions, and evaluations of their eyebrows, eyes, lips, and ear positions as changes that reflect pain or nociception. In this regard, research has found that dogs have anatomical configurations that allow them to generate changes in their expressions that similar canids—wolves, for example—cannot produce. Additionally, dogs can perceive emotions similar to those of their human tutors due to close human-animal interaction. This phenomenon—called “emotional contagion”—is triggered precisely by the dog’s capacity to identify their owners’ gestures and then react by emitting responses with either similar or opposed expressions that correspond to positive or negative stimuli, respectively. In conclusion, facial expressions are essential to maintaining social interaction between dogs and other species, as in their bond with humans. Moreover, this provides valuable information on emotions and the perception of pain, so in dogs, they can serve as valuable elements for recognizing and evaluating pain in clinical settings.
... Recently, some animal studies have explored this area in mice [49], rats [25], horses [27], rabbits [50] and cats [51]. Until recently, scientific interest in the facial expressions of emotions in non-human animals centred primarily on negative experiences such as pain and suffering, while neglecting the importance of evaluating and promoting positive experiences [52]. ...
Article
In many animal species, facial expressions are key elements for recognising emotions and numerous types of social interaction. Emotions are complex reactions that allow individuals to cope with full events that have either positive or negative meaning and involve certain neurophysiological responses proper to each emotion and species. Regulating emotional states requires integrating a whole series of responses –peripheral, autonomous, endocrine and muscular– that entail activating various sub-cortical structures, including the amygdale, hypothalamus and brainstem. In recent decades, interest in the emotions expressed by animals has grown, and researchers have come to understand that some problems of animal welfare can be detected by examining and comprehending the emotional experiences that animals may suffer, and identifying how they demonstrate their reactions through facial expressions and corporal postures. The objective of this review is to examine recent literature on aspects related to the function of the emotions and facial expressions in certain domestic species:–cats, dogs, rats, sheep, horses and pigs– and propose that understanding facial expressions can be useful as a complement to existing tools in assessing welfare and working with, or doing research on, these species.
... Impaired well-being of animals can be assessed by behavioral, biochemical, physiological, 12 and physical parameters [3]. In recent years, methods to analyze the facial expressions of pain, 13 analogous to the facial action coding system (FACS) for humans [4], were developed for various 14 animal species, e.g., mice, rats, rabbits, cats, horses, cows, sheep, and piglets [5][6][7][8][9][10][11][12][13][14]. The 15 so-called Grimace Scales are thought to measure the presence or absence of grimacing 16 associated with pain. ...
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Assessing the well-being of an animal is hindered by the limitations of efficient communication between humans and animals. Instead of direct communication, a variety of behavioral, biochemical, physiological, and physical parameters are employed to evaluate the well-being of an animal. Especially in the field of biomedical research, scientifically sound tools to assess pain, suffering, and distress for experimental animals are highly demanded due to ethical and legal reasons. For mice, the most commonly used laboratory animals, a valuable tool is the Mouse Grimace Scale (MGS), a coding system for facial expressions of pain in mice which has been shown to be accurate and reliable. Currently, MGS scoring is very time and effort consuming as it is manually performed by humans being thoroughly trained in using this method. Therefore, we aim to develop a fully automated system for the surveillance of well-being in mice. Our work introduces a semi-automated pipeline as a first step towards this goal. We use and provide a new data set of images of black-furred laboratory mice that were moving freely, thus the images contain natural variation with regard to perspective and background. The analysis of this data set is therefore more challenging but reflects realistic conditions as it would be obtainable without human intervention. Images were obtained after anesthesia (with isoflurane or ketamine/xylazine combination) and surgery (castration). We deploy two pre-trained state of the art deep convolutional neural network (CNN) architectures (ResNet50 and InceptionV3) and compare to a third CNN architecture without pre-training. Depending on the particular treatment, we achieve an accuracy of up to 99% for binary “pain”/”no-pain” classification. Author summary In the field of animal research, it is crucial to assess the well-being of an animal. For mice, the most commonly used laboratory animals, there is a variety of indicators for well-being. Especially the facial expression of a mouse can give us important information on its well-being state. However, currently the surveillance of well-being can only be ensured if a human is present. Therefore, we developed a first approach towards a fully automated surveillance of the well-being status of a mouse. We trained neural networks on face images of black-furred mice, which were either untreated or underwent anesthesia or surgery, to distinguish between an impaired and unimpaired well-being state. Our systems successfully learnt to assess whether the well-being of a mouse was impaired and, depending on the particular treatment, its decision was correct in up to 99%. A tool that visualizes the features used for the decision making process indicated that the decision was mainly based on the facial expressions of a mouse.
... Comparing grimace scales with pre-existing pain scales has some value in better understanding what is being measured and the relationships between different scales. This approach of convergent validity was applied during development of the Feline Grimace Scale, where the results of facial scoring were directly compared (Evangelista et al., 2019) to an existing composite measure pain scale (Calvo et al., 2014). In this case, the scales showed very strong correlation (r = 0.86, p < 0.001) indicating significant overlap in what was being measured. ...
Article
The measurement of pain in animals is surprisingly complex, and remains a critical issue in veterinary care and biomedical research. Based on the known utility of pain measurement via facial expression in verbal and especially non-verbal human populations, “grimace scales” were first developed a decade ago for use in rodents and now exist for 10 different mammalian species. This review details the background context, historical development, features (including duration), psychometric properties, modulatory factors, and impact of animal grimace scales for pain.
... Each feature is given a score of 0 (not present), 1 (moderate) or 2 (severe), which can be scored with remarkably high reliability and accuracy. Although the grimace scale has been readily evaluated in mice 11,14,15 and rats 12,16 , other grimace scales have been developed to capture 'pain faces' in horses 17 , cats 18 , rabbits 19 , sheep 20 and ferrets 21 , which have helped to evaluate postoperative pain across species. ...
Article
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Most research laboratories abide by guidelines and mandates set by their research institution regarding the administration of analgesics to control pain during the postoperative period. Unfortunately, measuring pain originating from the head is difficult, making adequate decisions regarding pain control following stereotaxic surgery problematic. In addition, most postsurgical analgesia protocols require multiple injections over several days, which may cause stress and distress during a critical recovery period. Here we sought to (1) assess the degree of postoperative pain following craniotomy in mice, (2) compare the efficacy of three common rodent analgesics (carprofen, meloxicam and buprenorphine) for reducing this pain and (3) determine whether the route of administration (injected or self-administered through the drinking supply) influenced pain relief post-craniotomy. Using the mouse grimace scale (MGS), we found that injectable analgesics were significantly more effective at relieving post-craniotomy pain, however, both routes of administration decreased pain scores in the first 24 h postsurgery. Specifically, buprenorphine administered independently of administration route was the most effective at reducing MGS scores, however, female mice showed greater sensitivity to carprofen when administered through the water supply. Although it is necessary to provide laboratory animals with analgesics after an invasive procedure, there remains a gap in the literature regarding the degree of craniotomy-related pain in rodents and the efficacy of alternative routes of administration. Our study highlights the limitations of administering drugs through the drinking supply, even at doses that are considered to be higher than those currently recommended by most research institutions for treating pain of mild to moderate severity.
... Efforts to use facial expressions as proxies for affective states and animal welfare have been made (Descovich et al., 2017). Langford et al. (2010) were among the first to use facial expressions and to explore the existence of a "pain face" in mice, which has been replicated in other species (Holden et al., 2014;MacRae et al., 2018;McLennan, 2018). Interestingly, orbital tightening is one of the key facial action units found in the human "pain face" (Prkachin, 1992) and has been found in many species in response to pain, but has not yet been explored in cattle. ...
Article
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Affective states, which refer to feelings or emotions, are a key component of animal welfare, but these are also difficult to assess. Drawing upon a body of theoretical and applied work, we critically review the scientific literature on the assessment of affective states in animals, drawing examples where possible from research on dairy cattle, and highlighting the strengths and weaknesses of scientific methods used to assess affective states in animals. We adopt the “valence/arousal” framework, describing affect as a 2-dimensional space (with valence referring to whether an experience is positive or negative, and arousal referring to the intensity of the experience). We conclude that spontaneous physiological and behavioral responses typically reflect arousal, whereas learned responses can be valuable when investigating valence. We also conclude that the assessment of affective states can be furthered using mood assessments and that the use of drug treatments with known emotional effects in humans can be helpful in the assessment of specific affective states in animals.
... 6 In a previous study, changes in ear and muzzle position had been identified in painful versus non-painful cats ( Figure 5). 23 Recently, development of a Feline Grimace Scale revealed further differences between painful and non-painful cats. 24 Five 'action units' were ...
Article
Practical relevance: Pain assessment has gained much attention in recent years as a means of improving pain management and treatment standards. It has become an elemental part of feline practice with ultimate benefit to feline health and welfare. Currently pain assessment involves mostly the investigation of sensory-discriminative (intensity, location and duration) and affective-motivational (emotional) domains of pain. Specific behaviors associated with acute pain have been identified and constitute the basis for its assessment in cats. Recent advances: The publication of pain scales with reported validation - the UNESP-Botucatu multidimensional composite pain scale and the Glasgow feline composite measure pain scale -and species-specific studies have advanced our knowledge on the subject. Facial expressions have also been shown to be different between painful and non-painful cats, and very recently the Feline Grimace Scale has been validated as a tool for acute pain assessment. Clinical challenges: Despite recent advances, several challenges still exist. For instance, the effects of disease and sedation on pain scoring/ assessment are unknown. Also, specific painful conditions (eg, dental pain) have not been systematically investigated. The development and validation of instruments for pain assessment by cat owners is warranted, as these tools are currently lacking. Aims: This article reviews the use, advantages, disadvantages and limitations of the two validated pain scales, and presents a practical, stepwise approach to feline pain recognition and assessment using a dynamic and interactive process. The authors also offer perspectives regarding current challenges and future directions.
... Each feature is given a score of 0 (not present), 1 (moderate) or 2 (severe), which can be scored with remarkably high reliability and accuracy. Although the grimace scale has been readily evaluated in mice 11,14,15 and rats 12,16 , other grimace scales have been developed to capture 'pain faces' in horses 17 , cats 18 , rabbits 19 , sheep 20 and ferrets 21 , which have helped to evaluate postoperative pain across species. ...
Preprint
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Most research laboratories abide by guidelines and mandates set by their research institution regarding the administration of analgesics to control pain during the postoperative period. Unfortunately, measuring pain originating from the head is difficult, making adequate decisions regarding pain control following stereotaxic surgery problematic. In addition, most postsurgical analgesia protocols require multiple injections over several days, which may cause stress and distress during a critical recovery period. Here we sought to 1) assess the degree of postoperative pain following craniotomy in mice, 2) compare the efficacy of three common rodent analgesics (carprofen, meloxicam and buprenorphine) for reducing this pain and 3) determine whether the route of administration (injected or self-administered through the water supply) influenced pain relief post-craniotomy. Using the mouse grimace scale (MGS), we found that injectable analgesics were significantly more effective at relieving post-craniotomy pain, however, both routes of administration decreased pain scores in the first 24 h post-surgery. Specifically, buprenorphine administered independently of administration route was the most effective at reducing MGS scores, however, female mice showed greater sensitivity to carprofen when administered through the water supply. Although it is necessary to provide laboratory animals with analgesics after an invasive procedure, there remains a gap in the literature regarding the degree of craniotomy-related pain in rodents and the efficacy of alternative routes of administration. Our study highlights the limitations of administering drugs through the water supply, even at doses that are considered to be higher than those currently recommended by most research institutions for treating pain of mild to moderate severity.
... Impaired well-being of animals can be assessed by behavioral, biochemical, physiological, and physical parameters [3]. In recent years, methods to analyze the facial expressions of pain, analogous to the facial action coding system (FACS) for humans [4], were developed for various animal species, e.g., mice, rats, rabbits, cats, horses, cows, sheep, and piglets [5][6][7][8][9][10][11][12][13][14]. The so-called Grimace Scales are thought to measure the presence or absence of grimacing associated with pain. ...
... Table 5. Comparative results between mainstream micro-expression recognition algorithms and our algorithm Algorithm Accuracy LBP-TOP [23] 40.09% CNN-LSTM [24] 62.19% STRCN-A [25] 56.82% ELRCN-SE [26] 48.21% CLBP-TOP (S+M) [27] 45.92% Our algorithm 58.39% ...
... Linear distances between specific facial landmarks and the quantification of changes in facial shape for the study of pain in cats have been published (Holden et al., 2014;Finka et al., 2019). Recently, a facial expression-based scoring system has been proposed for assessing acute pain in cats, namely the Feline Grimace Scale (FGS). ...
Article
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Background The Feline Grimace Scale (FGS) is a facial expression-based scoring system for acute pain assessment in cats with reported validity using image assessment. The aims of this study were to investigate the clinical applicability of the FGS in real-time when compared with image assessment, and to evaluate the influence of sedation and surgery on FGS scores in cats. Methods Sixty-five female cats (age: 1.37 ± 0.9 years and body weight: 2.85 ± 0.76 kg) were included in a prospective, randomized, clinical trial. Cats were sedated with intramuscular acepromazine and buprenorphine. Following induction with propofol, anesthesia was maintained with isoflurane and cats underwent ovariohysterectomy (OVH). Pain was evaluated at baseline, 15 min after sedation, and at 0.5, 1, 2, 3, 4, 6, 8, 12 and 24 h after extubation using the FGS in real-time (FGS-RT). Cats were video-recorded simultaneously at baseline, 15 min after sedation, and at 2, 6, 12, and 24 h after extubation for subsequent image assessment (FGS-IMG), which was performed six months later by the same observer. The agreement between FGS-RT and FGS-IMG scores was calculated using the Bland & Altman method for repeated measures. The effects of sedation (baseline versus 15 min) and OVH (baseline versus 24 h) were assessed using linear mixed models. Responsiveness to the administration of rescue analgesia (FGS scores before versus one hour after) was assessed using paired t-tests. Results Minimal bias (−0.057) and narrow limits of agreement (−0.351 to 0.237) were observed between the FGS-IMG and FGS-RT. Scores at baseline (FGS-RT: 0.16 ± 0.13 and FGS-IMG: 0.14 ± 0.13) were not different after sedation (FGS-RT: 0.2 ± 0.15, p = 0.39 and FGS-IMG: 0.16 ± 0.15, p = 0.99) nor at 24 h after extubation (FGS-RT: 0.16 ± 0.12, p = 0.99 and FGS-IMG: 0.12 ± 0.12, p = 0.96). Thirteen cats required rescue analgesia; their FGS scores were lower one hour after analgesic administration (FGS-RT: 0.21 ± 0.18 and FGS-IMG: 0.18 ± 0.17) than before (FGS-RT: 0.47 ± 0.24, p = 0.0005 and FGS-IMG: 0.45 ± 0.19, p = 0.015). Conclusions Real-time assessment slightly overestimates image scoring; however, with minimal clinical impact. Sedation with acepromazine-buprenorphine and ovariohysterectomy using a balanced anesthetic protocol did not influence the FGS scores. Responsiveness to analgesic administration was observed with both the FGS-RT and FGS-IMG.
... Impaired well-being of animals can be assessed by behavioral, biochemical, physiological, and physical parameters [3]. In recent years, methods to analyze the facial expressions of pain, analogous to the facial action coding system (FACS) for humans [4], were developed for various animal species, e.g., mice, rats, rabbits, cats, horses, cows, sheep, and piglets [5][6][7][8][9][10][11][12][13][14]. The so-called Grimace Scales are thought to measure the presence or absence of grimacing associated with pain. ...
Article
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Assessing the well-being of an animal is hindered by the limitations of efficient communication between humans and animals. Instead of direct communication, a variety of parameters are employed to evaluate the well-being of an animal. Especially in the field of biomedical research, scientifically sound tools to assess pain, suffering, and distress for experimental animals are highly demanded due to ethical and legal reasons. For mice, the most commonly used laboratory animals, a valuable tool is the Mouse Grimace Scale (MGS), a coding system for facial expressions of pain in mice. We aim to develop a fully automated system for the surveillance of post-surgical and post-anesthetic effects in mice. Our work introduces a semi-automated pipeline as a first step towards this goal. A new data set of images of black-furred laboratory mice that were moving freely is used and provided. Images were obtained after anesthesia (with isoflurane or ketamine/xylazine combination) and surgery (castration). We deploy two pre-trained state of the art deep convolutional neural network (CNN) architectures (ResNet50 and InceptionV3) and compare to a third CNN architecture without pre-training. Depending on the particular treatment, we achieve an accuracy of up to 99% for the recognition of the absence or presence of post-surgical and/or post-anesthetic effects on the facial expression.
... (6). Facial expression evaluation scale: Simple and intuitive observation of facial expression changes, such as mental discomfort, changes in hair luster and eye socket contraction [97,98]. The experimental method can refer to the study of Langford et al [99]. ...
Article
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Chronic pain is a common symptom of most clinical diseases, which seriously affects the psychosomatic health of patients and brings some pain to patients. Due to its pathological mechanism is very complicated and the treatment of chronic pain has always been a difficult problem in clinical. Normally, drugs are usually used to relieve pain, but the analgesic effect is not good, especially for cancer pain patients, the analgesic effect is poor. Therefore, exploring the pathogenesis and treatment of chronic pain has aroused the interest of many researchers. A large number of studies have shown that the role of ATP and P2X4 receptor (P2X4R) play an important role in the pathogenesis of chronic pain. P2X4R is dependent on ATP ligand-gated ion channel receptor, which can be activated by ATP and plays an important role in the information transmission of nerve system and the formation of pain. Therefore, in this paper, we comprehensively described the structure and biological functions of P2X4R, and outlined behavioral evaluation methods of chronic pain models. Moreover, we also explored the inherent relationship between P2X4R and chronic pain, and described the therapeutic effect of P2X4R antagonist on chronic pain, and provided some valuable help for the treatment of chronic pain.
... NFCS is adapted from the Facial Action Coding System, which is anatomically based and identifies minimal units of facial movement called Action Units with detailed descriptions of the resulting changes in facial appearance (Ekman and Friesen, 1978). This approach has provided the basis for a framework for pain assessment in animals, and has resulted in grimace scales being developed for mice (Langford et al., 2010), rats (Sotocinal et al., 2011), rabbits (Keating et al., 2012), horses (Dalla Costa et al., 2014), cats (Holden et al., 2014), sheep (McLennan et al., 2016), pigs (Di Giminiani et al., 2016) and ferrets (Reijgwart et al., 2017). Facial expressions provide a non-invasive means of pain assessment that exploits the natural tendency of humans to focus on the face when gauging pain (Williams, 2002), and can be used to assess pain ranging from mild to severe . ...
Article
There are no proven species-specific indicators of pain in harbour seals (Phoca vitulina). The analysis of facial expressions has proven to be a repeatable, accurate and valid method of identifying pain in multiple species, but facial expressions have not been examined in any species of pinniped. This study investigated whether harbour seals’ facial expressions and other behaviours changed immediately after a potentially painful procedure. Forty-seven pups (healthy, >60 d old) at a rehabilitation facility were video-recorded during routine procedures of flipper tagging and microchipping, which are normally done without analgesia. Eight pups were used to generate an ethogram of the facial and behavioural changes seen, 19 pups to compare the behaviours before and after the procedures (Experiment 1), 10 pups in a cross-over experiment comparing responses to real and sham procedures (Experiment 2), and 10 pups to pilot-test a possible analgesic (Experiment 3). For each seal, two observers (Experiment 1) and one observer (Experiments 2 and 3), blind to treatment, watched 90-s video clips recorded just before and just after the procedures. The observers, one experienced with the species and the other not, also made a subjective judgement of whether pain was present or absent for each clip in Experiment 1. In all three experiments, orbital tightening increased from before to after tagging and microchipping (p < 0.0001), whereas the behaviours of looking around (p < 0.01) and struggling (p < 0.05) decreased. Blinking (p < 0.05) decreased in Experiments 1 and 2 while trembling (p < 0.01) decreased only in Experiment 1. Inter-observer reliability ranged from r = 0.82 to 0.92 for these five types of behaviour. In Experiment 2, sham treatment produced no similar changes. In Experiment 3, the procedures produced similar changes likely because the single analgesic/dosage tested was ineffective. For both observers, the subjective scoring of presence or absence of pain corresponded closely to whether or not the procedures had been performed (95% correspondence for experienced and 89% for inexperienced). These results show promise for facial expressions and other behaviours to be used to assess potentially painful procedures in seals.
... In fact, facial expressions to communicate affect are common among several species and have been thoroughly described using a taxonomy of facial movements in humans (Ekman et al., 2002;Ekman & Wallace, 1978;Hjortsjö, 1969), chimpanzees (Vick et al., 2007), and horses (Wathan et al., 2015). In response to noxious stimuli, numerous studies have reported that facial grimacing is present in mice (Langford, Bailey, et al., 2010), rats (Sotocinal et al., 2011), rabbits (Keating et al., 2012), horses (Dalla Costa et al., 2014), sheep (Guesgen et al., 2016;Häger et al., 2017;McLennan et al., 2016), piglets (Di Giminiani et al., 2016;Viscardi et al., 2017), ferrets (Reijgwart et al., 2017), and cats (Finka et al., 2019;Holden et al., 2014) with each animal displaying features that are unique to that species (i.e., ear position will change in mice, while humans are not able to change this feature of their face). ...
Chapter
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Within the social environment pain can serve as a tool used to communicate information about our status and well-being. Viewed in this light, it is important to appreciate that pain perception and expression can change depending on our social history, social interactions and observation of pain within our immediate environment.
... While the majority of studies appraised by the review utilised an NRS to measure feline pain, only the UNESP-Botucatu Multidimensional Composition Pain Scale was found to demonstrate good validity, reliability and sensitivity 6 . All four papers, thus, could have benefited from incorporating all or part of the UNESP-Botucatu Multidimensional Composition Pain Scale into their methodology 16,21,[27][28][29] . ...
Article
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PICO question In adult cats undergoing a venepuncture procedure, does the application of a topical lidocaine based anaesthetic to the skin at the venepuncture site reduce the severity of signs associated with pain when compared to no topical anaesthetic? Clinical bottom line Category of research question Treatment The number and type of study designs reviewed Four papers were critically reviewed. Three were prospective, double-blind, randomised, controlled clinical trials, and one was a prospective, double-blind, controlled experimental trial Strength of evidence Moderate Outcomes reported The application of Eutectic Mixture of Local Anaesthetics (EMLA™) cream to clipped skin over the procedure site, a minimum of 30 minutes prior to the venepuncture procedure, significantly reduced the severity of pain-associated behaviours during jugular phlebotomy in healthy, conscious feline patients when compared to a placebo1,2. In felines sedated with dexmedetomidine and either methadone or nalbuphine, the administration of EMLA™ cream to clipped skin for 20 minutes significantly decreased the severity of pain responses during intravenous (IV) cephalic vein catheterisation when compared to no treatment3. In clinically unwell feline patients, the use of EMLA™ cream on clipped skin at the site of jugular catheterisation 60 minutes prior demonstrated reduced pain responses compared to a placebo, but further investigation with a larger sample size is required to verify statistical significance4 Conclusion The available evidence moderately supports the hypothesis that EMLA™ cream is an effective and noninvasive treatment for providing enhanced pain-relief during jugular and cephalic vein phlebotomy for the purposes of blood collection and catheterisation, respectively. The areas for treatment should be clipped free of hair, and the cream applied for a minimum of 30 minutes in non-sedated cats and 20 minutes in cats sedated with dexmedetomidine and either methadone or nalbuphine. Moreover, when applied to normal, intact skin and covered by an occlusive bandage to avoid ingestion, it is well supported by supplementary evidence that EMLA™ cream has a wide safety margin for topical use in cats4,5 How to apply this evidence in practice The application of evidence into practice should take into account multiple factors, not limited to: individual clinical expertise, patient’s circumstances and owners’ values, country, location or clinic where you work, the individual case in front of you, the availability of therapies and resources. Knowledge Summaries are a resource to help reinforce or inform decision making. They do not override the responsibility or judgement of the practitioner to do what is best for the animal in their care.
... Efforts to use facial expressions as proxies for affective states and animal welfare have been made (Descovich et al., 2017). Langford et al. (2010) were among the first to use facial expressions and to explore the existence of a 'pain face' in mice, which has been replicated in other species (Holden et al., 2014;MacRae et al., 2018;McLennan, 2018). Interestingly, orbital tightening is one of the key facial action unit found in the human 'pain face' (Prkachin, 1992) and has been found in many species in response to pain, but has not yet been explored in cattle. ...
Thesis
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Whether they live in our homes, farms or laboratories, many animals are subjected to painful procedures. In humans, pain assessment is mostly done through verbal self report, but the assessment of pain in non-verbal humans and animals remains a challenging task. Pain can be divided in two main components: a reflex response, and an emotional experience. The focus of pain research has largely been centered around reflex responses when animals (and human neonates until recently) are the ones subjected to pain. The aim of this thesis was to address this gap by developing a method to assess the emotional experience (or ‘affective state’) that dairy calves go through during painful procedures. To do so, the focus of our novel approach was on how animals formed memories of procedures they were subjected to. In the first chapter, I reviewed the literature on the assessment of emotion in dairy cattle. I highlighted that many measures reflect how aroused animals are rather than whether they are in a positive or negative state (valence), but that measures based on cognition were promising in evaluating valence. In the second chapter, I studied the pain caused by different injection methods by looking at how much milk calves were willing to give up to avoid injections. Although all methods were more aversive than not receiving an injection, intramuscular injections were more aversive than subcutaneous or intranasal. In the third, fourth and fifth chapter, I studied how calves remembered different methods of disbudding (a procedure that prevents horn growth) by looking at how much they would avoid the place where they experienced the procedure. I found that calves remember disbudding as negative and that learned aversion is reduced if calves are provided pain control both during and after the procedure. In summary, calves showed not to be limited to a ‘knee-jerk’ response to pain. Rather, they formed impactful memories that affected their future behaviour, exhibiting complex emotional processing of pain.
... Most nonhuman animals produce an automatic involuntary display of facial expressions in response to specific emotioneliciting stimuli. Lately, there has been an increase in the number of studies on the facial expression of pain in different animal species (Langford et al., 2010;Sotocina et al., 2011;Keating et al., 2012;Costa et al., 2014;Holden et al., 2014;Guesgen et al., 2016;McLennan et al., 2016;Finka et al., 2019). Further, it has been proposed that facial expression may reliably indicate both negative and positive-emotional states and thus have a substantial potential in animal welfare assessment (Descovich et al., 2017). ...
Article
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Although there have been a growing number of studies focusing on dog welfare, the research field concerning dog positive-emotion assessment remains mostly unexplored. This paper aims to provide a state-of-the-art review and summary of the scattered and disperse research on dog positive-emotion assessment. The review notably details the current advancement in dog positive-emotion research, what approaches, measures, methods, and techniques have been implemented so far in emotion perception, processing, and response assessment. Moreover, we propose possible future research directions for short-term emotion as well as longer-term emotional states assessment in dogs. The review ends by identifying and addressing some methodological limitations and by pointing out further methodological research needs.
... which has been developed for mice, rats, rabbits, ferrets, cats, sheep, pigs, horses, and even harbor seals. 3,4,9,11,13,15,19,22,26,30,37,45,50 The use of a proxy indicator, such as burrowing and time-to-integrate-to-nest in mice and time-to-consume in guinea pigs, can be used as an additional tool for the evaluation of pain. 5,17,18,35,38 Because none of the previously mentioned assessment techniques were specific to hamsters, we here explored using these approaches to detect pain in Syrian hamsters that underwent laparotomy in a laboratory setting. ...
Article
Despite the use of Syrian hamsters (Mesocricetus auratus) in research, little is known about the evaluation of pain in this species. This study investigated whether the frequency of certain behaviors, a grimace scale, the treat-take-test proxy indicator, body weight, water consumption, and coat appearance could be monitored as signs of postoperative pain in hamsters in a research setting. Animals underwent no manipulation, anesthesia only or laparotomy under anesthesia. An ethogram was constructed and used to determine the frequencies of pain, active and passive behaviors by in-person and remote videorecording observation methods. The Syrian Hamster Grimace Scale (SHGS) was developed for evaluation of facial expressions before and after the surgery. The treat-take-test assessed whether surgery would affect the animals’ motivation to take a high-value food item from a handler. The hypothesis was that behavior frequency, grimace scale, treat-take-test score, body weight, water consumption, and coat appearance would change from baseline in the surgery group but not in the no-intervention and anesthesia-only groups. At several time points, pain and passive behaviors were higher than during baseline in the surgery group but not the anesthesia-only and no-intervention groups. The SHGS score increased from baseline scores in 3 of the 9 animals studied after surgery. The frequency of pain behaviors and SHGS scores were highly specific but poorly sensitive tools to identify animals with pain. Behaviors in the pain category were exhibited by chiefly, but not solely, animals that underwent the laparotomy. Also, many animals that underwent laparotomy did not show behaviors in the pain category. Treat-take-test scores, body weight, water consumption, and coat appearance did not change from baseline in any of the 3 groups. Overall, the methods we tested for identifying Syrian hamsters experiencing postoperative pain were not effective. More research is needed regarding clinically relevant strategies to assess pain in Syrian hamsters.
... It is now clear that the mouse (Langford et al. 2010), rat (Sotocinal et al. 2011), rabbit, (Keating et al. 2012), horse (Dalla Costa et al. 2014) and cat (Holden et al. 2014) make a specific facial grimace following noxious stimulation. Based directly on human facial pain scales (Williams, 2002), highly reliable and accurate facial grimace scales for these species have been developed. ...
Article
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... Additional instruments used for the assessment of facial expressions in animals were identified in the literature search including: Facial expression tool for cats [32]; Equine Pain Face [25]; Cow Pain Scale [24]; Piglet Grimace Scale (PGS-a) [23] and three other instruments used for the identification of AU in seals [46], beef cattle [68] and donkeys (Donkey Grimace Scale, DGS) [72] (Table 6). However, these studies were not included in this systematic review either because the instrument was not meant to be used alone (incorporated into another instrument) or because there were no numerical scores to allow for a final score calculation. ...
Article
Facial expressions of pain have been identified in several animal species. The aim of this systematic review was to provide evidence on the measurement properties of grimace scales for pain assessment. The protocol was registered (SyRF#21-Nov-2019) and the study is reported according to the PRISMA guidelines. Studies reporting the development, validation, and the assessment of measurement properties of grimace scales were included. Data extraction and assessment were performed by two investigators, following the Consensus-based Standards for the Selection of Health Measurement Instruments (COSMIN) guidelines. Six categories of measurement properties were assessed: internal consistency, reliability, measurement error, criterion and construct validity, and responsiveness. Overall strength of evidence (high, moderate, low) of each instrument was based on methodological quality, number of studies and studies' findings. Twelve scales for nine species were included (mice, rats, rabbits, horses, piglets, sheep/lamb, ferrets, cats and donkeys). Considerable variability regarding their development and measurement properties was observed. The Mouse, Rat, Horse and Feline Grimace Scales exhibited high level of evidence. The Rabbit, Lamb, Piglet and Ferret Grimace Scales and Sheep Pain Facial Expression Scale exhibited moderate level of evidence. The Sheep Grimace Scale, EQUUS-FAP and EQUUS-Donkey-FAP exhibited low level of evidence for measurement properties. Construct validity was the most reported measurement property. Reliability and other forms of validity have been understudied. This systematic review identified gaps in knowledge on the measurement properties of grimace scales. Further studies should focus on improving psychometric testing, instrument refinement and the use of grimace scales for pain assessment in non-human mammals.
... Temporal tension and ear position was the most imprecise FAU in sows, probably due to the ear size of sows and/or their position when sows were lying laterally (because they could cover parts of the face). In contrast, Ear position was a very good indicator in other species' facial scales, being considered to be one of the best FAUs to evaluate pain in sheep [9,11], cats [25], rats [5], and mice [4]. There is even a horse grimace scale study [12] where all of the observers were able to evaluate horses' ears. ...
Article
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Changes in facial expression have been shown to be a useful tool to assess pain severity in humans and animals, but facial scales have not yet been developed for all species. A facial expression scale in sows was developed using farrowing as a pain model. Five potential facial zones were identified: (i) Tension above eyes, (ii) Snout angle, (iii) Neck tension, (iv) Temporal tension and ear position (v), and Cheek tension. Facial zones were examined through 263 images of a total of 21 sows at farrowing, characterizing moments of non-pain (19 days post-farrowing; score 0), moderate pain (time interval between the delivery of two consecutive piglets; score 1) and severe pain (during active piglet delivery; score 2). Images were evaluated by a “Silver Standard” observer with experience in sows’ facial expressions, and by a group of eight animal welfare scientists, without experience in it, but who received a one-hour training session on how to assess pain in sows’ faces. Intra- and inter-observer reliability of the facial expression ranged from moderate to very good for all facial expression zones, with Tension above eyes, Snout angle, and Neck tension showing the highest reliability. In conclusion, monitoring facial expressions seems to be a useful tool to assess pain caused by farrowing.
... The block was performed under a short sedation with alfaxalone IV to effect and was performed twice, 3 days apart, in response to pain evaluations using the Feline Grimace Scale. 14,15 Enteral nutrition with urinary food (Urinary Care, Royal Canin, Aimargues, France) expanded by an amino acid solution (Aminoplasmal, B. Braun, Maria Enzersdorf, Austria) via an oesophageal tube was provided for 7 days following surgery to accelerate restoration of normal plasma albumin levels and promote wound healing. ...
Article
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This case report describes a low‐grade malignant B‐cell lymphoma (lymphocytic lymphoma) in a 14‐year‐old mixed breed cat, diagnosed by bronchoscopy and diagnostic imaging (radiography, ultrasound and computed tomography). The patient was treated with surgery, and postoperative complications included blindness and a severe mycoplasma infection of the thoracic cavity, which was treated using a vacuum‐assisted closure device. Long‐term therapy with prednisolone and chlorambucil and outcome with a survival time of 1385 days after discharge are also presented.
... Thermal and mechanical nociception and pain tests commonly used in rodents have been adapted for these large animal models, such as facial expression analysis with the Grimace Scales (Holden et al., 2014;de Grauw and van Loon, 2016). For OA large animal models, subjective lameness scoring and kinetic gait analysis are also a widely method to assess OA pain (Moreau et al., 2014). ...
Article
Chronic pain is a maladaptive neurological disease that remains a major health problem. A deepening of our knowledge on mechanisms that cause pain is a prerequisite to developing novel treatments. A large variety of animal models of pain has been developed that recapitulate the diverse symptoms of different pain pathologies. These models reproduce different pain phenotypes and remain necessary to examine the multidimensional aspects of pain and understand the cellular and molecular basis underlying pain conditions. In this review, we propose an overview of animal models, from simple organisms to rodents and non-human primates and the specific traits of pain pathologies they model. We present the main behavioral tests for assessing pain and investing the underpinning mechanisms of chronic pathological pain. The validity of animal models is analysed based on their ability to mimic human clinical diseases and to predict treatment outcomes. Refine characterization of pathological phenotypes also requires to consider pain globally using specific procedures dedicated to study emotional comorbidities of pain. We discuss the limitations of pain models when research findings fail to be translated from animal models to human clinics. But we also point to some recent successes in analgesic drug development that highlight strategies for improving the predictive validity of animal models of pain. Finally, we emphasize the importance of using assortments of preclinical pain models to identify pain subtype mechanisms, and to foster the development of better analgesics.
... A recent study showed that most veterinarians fail to assess pain in cats based on the sole evaluation of their facial expressions (Holden et al. 2014). These results call for the need to develop tools to help owners and professionals in understanding emotional expressions of pleasure and pain in cats. ...
... [3][4][5][6] Moreover, there are now three scales with reported validity for acute feline pain assessment that take into consideration facial expressions and the cat's unique behaviour. [7][8][9][10] All three provide clinical guidance on the need for analgesia when a cut-off value is reached. However, rescue interventions may be administered even when the cut-off is not reached if the veterinarian feels that the cat could be in pain. ...
Article
Practical relevance Increases in cat ownership worldwide mean more cats are requiring veterinary care. Illness, trauma and surgery can result in acute pain, and effective management of pain is required for optimal feline welfare (ie, physical health and mental wellbeing). Validated pain assessment tools are available and pain management plans for the individual patient should incorporate pharmacological and non-pharmacological therapy. Preventive and multimodal analgesia, including local anaesthesia, are important principles of pain management, and the choice of analgesic drugs should take into account the type, severity and duration of pain, presence of comorbidities and avoidance of adverse effects. Nursing care, environmental modifications and cat friendly handling are likewise pivotal to the pain management plan, as is a team approach, involving the cat carer. Clinical challenges Pain has traditionally been under-recognised in cats. Pain assessment tools are not widely implemented, and signs of pain in this species may be subtle. The unique challenges of feline metabolism and comorbidities may lead to undertreatment of pain and the development of peripheral and central sensitisation. Lack of availability or experience with various analgesic drugs may compromise effective pain management. Evidence base These Guidelines have been created by a panel of experts and the International Society of Feline Medicine (ISFM) based on the available literature and the authors’ experience. They are aimed at general practitioners to assist in the assessment, prevention and management of acute pain in feline patients, and to provide a practical guide to selection and dosing of effective analgesic agents.
... Thermal and mechanical nociception and pain tests commonly used in rodents have been adapted for these large animal models, such as facial expression analysis with the Grimace Scales (de Grauw and van Loon, 2016;Holden et al., 2014). For OA large animal models, subjective lameness scoring and kinetic gait analysis are also a widely method to assess OA pain (Moreau et al., 2014). ...
Thesis
La douleur chronique souvent accompagnée d’anxiété et de dépression est un fléau mondial. La modulation de la douleur par les neuropeptides (NP) est bien connu au niveau des afférences primaires et de la moelle épinière. Peu de données sont toutefois disponibles sur leur rôle dans la douleur dans le cerveau. La famille relaxine comprend la relaxine, présente dans le système nerveux central (SNC) et qui possède des propriétés antifibrotiques, et la relaxine-3, strictement exprimée dans le SNC et qui présente des effets anxiolytiques et antidépressifs. Notre objectif est d’étudier la modulation de la douleur par les neuropeptides relaxine et relaxine-3 dans un modèle de douleur inflammatoire persistante chez la souris.Nos résultats démontrent que non seulement le système relaxine-3 / RXFP3, mais aussi le système relaxine / RXFP1 encore très peu exploré dans le SNC, ont des effets analgésiques en conditions de douleur inflammatoire. Les sites d'action de ces systèmes peptidergiques comprennent des régions corticales (cortex cingulaire, claustrum) et sous-corticales (amygdale) qui régulent les voies descendantes et l'intégration sensorielle dans la moelle épinière. Nos données mettent en évidence le potentiel thérapeutique de cette famille peptidergique dont les rôles dans la douleur n'avaient jamais été testés.
Article
Objectives: The aim of this study was to compare the Electronic von Frey Anaesthesiometer (EVF) and the Small Animal ALGOmeter (SMALGO), used to measure sensory thresholds in 13 healthy cats at both the stifle and the lumbosacral joint, in terms of inter-rater and inter-device reliability. Methods: Two independent observers carried out the sets of measurements in a randomised order, with a 45 min interval between them, in each cat. The inter-rater and inter-device reliability were evaluated by calculating the inter-rater correlation coefficient (ICC) for each pair of measurements. The Bland-Altman method was used as an additional tool to assess the level of agreement between the two algometers. Results: The mean ± SD sensory thresholds measured with the EVF were 311 ± 116 g and 378 ± 178 g for the stifle and for the lumbosacral junction, respectively, whereas those measured with the SMALGO were 391 ±172 g and 476 ± 172 g. The inter-rater reliability was fair (ICC >0.4) for each pair of measurements except those taken at the level of the stifle with the SMALGO, for which the level of agreement between observer A and B was poor (ICC = 0.01). The inter-device reliability was good (ICC = 0.73; P = 0.001). The repetition of the measurements affected reliability, as the thresholds obtained after the 45 min break were consistently lower than those measured during the first part of the trial ( P = 0.02). Conclusions and relevance: The EVF and the SMALGO may be used interchangeably in cats, especially when the area to be tested is the lumbosacral joint. However, when the thresholds are measured at the stifle, the inter-observer reliability is better with the EVF than with the SMALGO. The reliability decreases when the measurements are repeated within a short time interval, suggesting a limited clinical applicability of quantitative sensory testing with both algometers in cats.
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Animals cannot tell us that they are in pain; therefore, assessing pain in veterinary patients can be challenging. Two scales for evaluating acute pain in cats have been validated and can be used in everyday practice. This article describes these pain assessment scales and discusses how they can be used and interpreted to guide the use of analgesia in feline patients to the benefit of their welfare.
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Human expression of pain and others’ responses to it are explored using an evolutionary framework. Pain itself functions to promote recovery, and both the capacity to react to damaging stimuli and many behaviors showing the aversive nature of the event are widespread in animals. One of the behaviors, facial expression of pain, is described in detail, as it is a direct communication of pain to those close by, and is understood across ages, ethnicities, roles, and relationships. Those who observe another’s pain may respond in various ways, from empathy to exploitation. Evolutionary mechanisms help us understand the biases in how we perceive and judge behavior that indicates pain, and how this informs social responses to pain, particularly in clinical and caregiving settings.
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Effective management of pain is critical to the improvement of animal welfare. For this to happen, pain must be recognised and assessed in a variety of contexts. Pain is a complex phenomenon, making reliable, valid, and feasible measurement challenging. The use of facial expressions as a technique to assess pain in non-verbal human patients has been widely utilised for many years. More recently this technique has been developed for use in a number of non-human species: rodents, rabbits, ferrets, cats, sheep, pigs and horses. Facial expression scoring has been demonstrated to provide an effective means of identifying animal pain and in assessing its severity, overcoming some of the limitations of other measures for pain assessment in animals. However, there remain limitations and challenges to the use of facial expression as a welfare assessment tool which must be investigated. This paper reviews current facial expression pain scales ("Grimace Scales"), discussing the general conceptual and methodological issues faced when assessing pain, and highlighting the advantages of using facial expression scales over other pain assessment methods. We provide guidance on how facial expression scales should be developed so as to be valid and reliable, but we also provide guidance on how they should be used in clinical practice.
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Feline oral squamous cell carcinoma (FOSCC) is a common and naturally occurring condition that recapitulates many features of human head and neck cancer (HNC). In both species, there is need for improved strategies to reduce pain caused by HNC and its treatment. Research to benefit both species could be conducted using pet cats as a comparative model, but this prospect is limited by lack of validated methods for quantifying FOSCC-associated pain. A prospective non-randomized pilot study was performed for initial validation of: (1) a pet owner administered quality of life questionnaire and visual assessment scoring tool (FORQ/CLIENT); (2) a clinician assessment questionnaire (UFEPS/VET); (3) electronic von Frey testing [EVF]; and (4) Cochet-Bonnet (COBO) aesthesiometry. To assess intra-rater reliability, discriminatory ability, and responsiveness of each assay, 6 cats with sublingual SCC and 16 healthy control cats were enrolled. The intra-rater reliability was moderate-to-good for the clinical metrology instruments and EVF (intraclass correlation coefficient [ICC] ≥ 0.68), but poor for COBO (ICC = 0.21). FORQ/CLIENT scores were higher (worse quality of life) in FOSCC cats vs healthy controls. The internal reliability of FORQ/CLIENT scoring was high (Cronbach α = 0.92); sensitivity and specificity were excellent (100% when using cut-offs determined using receiver operating characteristic [ROC] curves). For the FORQ/CLIENT, there was strong and inverse correlation between scores from the questions and visual assessment ( r = − 0.77, r ² = 0.6, P < 0.0001). For the UFEPS/VET, Cronbach’s α was 0.74 (high reliability). Sensitivity and specificity were 100% and 94%, respectively, when using a cut-off score (3.5) based on ROC curves (Youden index of 0.94). Total UFEPS/VET scores were positively correlated with FORQ/CLIENT scores ( r ² = 0.72, P < 0.0001). Sensitivity of EVF and COBO ranged from 83 to 100% and specificity ranged from 56 to 94%. Cats with cancer were more sensitive around the face (lower response thresholds) and on the cornea (longer filament lengths) than control animals ( P < 0.03). Reduced pressure response thresholds were also observed at a distant site ( P = 0.0002) in cancer cats. After giving buprenorphine, EVF pressure response thresholds increased ( P = 0.04) near the mandible of cats with OSCC; the length of filament required to elicit a response in the COBO assay also improved (shortened; P = 0.017). Based on these preliminary assessments, the assays described herein had reasonable inter-rater reliability, and they were able to both discriminate between cats with and without oral cancer, and respond in a predictable manner to analgesic therapy. In cats with tongue cancer, there was evidence for regional peripheral sensitization, and widespread somatosensory sensitization. These results provide a basis for multi-dimensional assessments of pain and sensitivity in cats with oral SCC.
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Anesthesia and analgesia for dental patients can be a challenge. It is important to do a thorough workup on all these patients so that systemic diseases can be managed prior to anesthesia, if possible. The approaches to managing these patients are discussed. Up to date information is provided on local anesthetic blocks and analgesics that might be of use in managing these patients
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The social modulation of pain in humans has been neglected so far with respect to verbal as well as non-verbal communication of pain. The facial pain expression is a powerful way to communicate pain, and there are some theoretical accounts available on how social modulation may affect the encoding of the facial expression of pain. Some accounts, particularly in the pain field, are proximate explanations on the mechanisms involved, whereas an evolutionary psychology account takes a more comprehensive approach. A review of nine experimental studies revealed that in the majority of studies (6/9), social context had an effect on the facial pain expression, but results were inconsistent. Several conceptual and methodological issues are discussed which may explain these inconsistencies and could help in design of future experimental studies. This article is part of the Theo Murphy meeting issue ‘Evolution of mechanisms and behaviour important for pain’.
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The aim of this work was to compare three techniques of local blockade, as part of a multimodal protocol in cats submitted to videoassisted ovariectomy (OVH). This study included 38 cats, assigned to four groups (control; incisional block, intraperitoneal block and block of the ovarian arteriovenous complex). Pain was assessed using Analogue Visual Scale, Pain Scale of the UNESP and Composite Multimodal Pains Scale-Feline, prior and after surgery. Anesthetic and analgesic protocols provided adequate post-surgical analgesia in most cats. It is concluded that the intraperitoneal administration of lidocaine may be a useful technique to reduce trans-surgical pain, while the use of incisional infiltration with this medication improves early postoperative pain in videosurgeries.
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Objectives To evaluate the prevalence of complications during bone marrow sampling and associated patient and procedural factors in dogs and cats. Materials and Methods Retrospective cohort study, records were evaluated to identify dogs and cats that had bone marrow sampling between 2012 and 2019. Data including signalment, the presence of specific clinicopathological findings, anatomical site of bone marrow sampling, number of attempts, diagnostic quality of sampling, analgesia protocol and complications postprocedure were recorded. Results A total of 131 dogs and 29 cats were included in the study. Complications were recorded in 22 of 160 (14%) of cases. Pain was the most common complication of bone marrow sampling in 20 of 22 (91%) of cases with bruising reported in the remaining patients. A local anaesthetic block was used in 98 of 160 (61%) of patients. Clinical Significance Excluding pain, complications associated with bone marrow sampling were rare and no clear association were detected between patient or procedural variables. Haemorrhage and infection are rare complications in dogs and cats when thrombocytopenia and neutropenia are present. Peri‐procedure analgesia is strongly recommended to minimise complications.
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Anesthesia comprises several steps, which include pre‐anesthetic evaluation and pre‐medication; the induction, maintenance, and recovery phases of anesthesia; and post‐anesthetic care. During anesthesia dogs and cats may breathe room air or receive oxygen and/or inhalant agents via a face mask or following intubation. Oxygen supplementation is recommended in anesthetized animals. Standard operating procedures should be embraced in clinical practice: they improve safety, compliance, and accountability and ensure things are done in a consistent manner despite turnover of staff. Anesthesia and analgesia are key components to the success of a shelter's spay and neuter program. Anesthesia must be time and cost efficient and associated with a low morbidity and mortality rate. When appropriate anesthetic protocols are used that include multimodal analgesia, along with close monitoring by trained personnel and attention to detail, these goals can be achieved.
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Cats have unique anatomic, physiologic, and behavioral considerations that may influence analgesia and pain management. They present specific challenges that require an individualized, feline-specific approach. This article presents an overview of recent advances in feline pain management and their differences in relation to other species and evolves on its future challenges. The main specific anatomy and physiology of the cat and how it may affect analgesia is discussed. Validated pain assessment tools including the UNESP-Botucatu Multidimensional Composite Pain Scale, Glasgow Feline Composite Measure Pain Scale, and the Feline Grimace Scale are summarized.
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The aims of this study was to describe the presence, clinical manifestations, risk factors, quality of life and measurement of mechanical nociceptive threshold (MNT) of phantom limb complex in a feline population that underwent amputation of a limb. A questionnaire was developed containing 3 sections with a total of 71 closed-end questions. Clinical cases were retrospectively reviewed. The evaluation of MNT was conducted applying an algometer at the level of the stump of the amputated limb and exerting a gradually increasing pressure. Descriptive statistics and frequency distribution analyses were performed on the collected data. Chi-squared test or Fisher's exact test were used for assessment of the associations between categorical variables. A total of 27 amputee cats were included in the study. All owners answered the questionnaire, while the mechanical nociceptive threshold assessment was conducted in 44% patients. The most frequent reason for amputation was related to trauma. The presence of pain after limb amputation has been commonly described by owners. The time between diagnosis and amputation was found to be significantly associated with the presence of pain after amputation. The majority of owners described different manifestations of pain or discomfort both before and after amputation, with environmental and physical stress described as related to the onset of pain in some cases. Furthermore, a significant reduction of the nociceptive threshold in the amputated region was highlighted. This pilot study introduces previously unreported signs that may be interpreted as expressions of pain in amputee cats.
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The facial expressions of animals constitute a means of manifesting emotions, fulfilling functions related to social interactions in several species. Interest has come to use facial expressions as a tool for predicting intentions; in the case of aggression, for example, impeding attacks between individuals prevents negative economic and emotional impacts. Recent research has sought to associate facial expressions with painful events as tail-cropping and castration on the assumption that objective evaluations of the presence or absence of grimaces in pigs' snouts may allow us to determine the intensity of the pain they perceive. Furthermore, to continue developing scales that will complement the existing piglet grimace scale (PGS), which is not yet fully-validated in terms of reliability. Another area of research is interpreting expressions of fear during traumatic events like pre-slaughter handling. Also, the phenomenon of emotional contagion in groups of animals suggests the need to focus on their emotions, since recognizing them could allow us to prevent alterations of meat quality. These approaches reveal the need for a detailed compilation of the facial expressions of pigs based on current scientific literature regarding emotions, alimentation, and pain-related behavioral responses in pigs.
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The assessment of pain is critical for the welfare of horses, in particular when pain is induced by common management procedures such as castration. Existing pain assessment methods have several limitations, which reduce the applicability in everyday life. Assessment of facial expression changes, as a novel means of pain scoring, may offer numerous advantages and overcome some of these limitations. The objective of this study was to develop and validate a standardised pain scale based on facial expressions in horses (Horse Grimace Scale [HGS]). Forty stallions were assigned to one of two treatments and all animals underwent routine surgical castration under general anaesthesia. Group A (n = 19) received a single injection of Flunixin immediately before anaesthesia. Group B (n = 21) received Flunixin immediately before anaesthesia and then again, as an oral administration, six hours after the surgery. In addition, six horses were used as anaesthesia controls (C). These animals underwent non-invasive, indolent procedures, received the same treatment as group A, but did not undergo surgical procedures that could be accompanied with surgical pain. Changes in behaviour, composite pain scale (CPS) scores and horse grimace scale (HGS) scores were assessed before and 8-hours post-procedure. Only horses undergoing castration (Groups A and B) showed significantly greater HGS and CPS scores at 8-hours post compared to pre operatively. Further, maintenance behaviours such as explorative behaviour and alertness were also reduced. No difference was observed between the two analgesic treatment groups. The Horse Grimace Scale potentially offers an effective and reliable method of assessing pain following routine castration in horses. However, auxiliary studies are required to evaluate different painful conditions and analgesic schedules.
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A scale validated in one language is not automatically valid in another language or culture. The purpose of this study was to validate the English version of the UNESP-Botucatu multidimensional composite pain scale (MCPS) to assess postoperative pain in cats. The English version was developed using translation, back-translation, and review by individuals with expertise in feline pain management. In sequence, validity and reliability tests were performed. Of the three domains identified by factor analysis, the internal consistency was excellent for 'pain expression' and 'psychomotor change' (0.86 and 0.87) but not for 'physiological variables' (0.28). Relevant changes in pain scores at clinically distinct time points (e.g., post-surgery, post-analgesic therapy), confirmed the construct validity and responsiveness (Wilcoxon test, p < 0.001). Favorable correlation with the IVAS scores (p < 0.001) and moderate to very good agreement between blinded observers and 'gold standard' evaluations, supported criterion validity. The cut-off point for rescue analgesia was > 7 (range 0--30 points) with 96.5% sensitivity and 99.5% specificity. The English version of the UNESP-Botucatu-MCPS is a valid, reliable and responsive instrument for assessing acute pain in cats undergoing ovariohysterectomy, when used by anesthesiologists or anesthesia technicians. The cut-off point for rescue analgesia provides an additional tool for guiding analgesic therapy.
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In March 1996, a questionnaire was sent to 2000 veterinary surgeons primarily involved in small animal practice to assess their attitudes to perioperative analgesic therapy in dogs, cats and other small mammals. This paper is concerned only with the data relevant to cats, analgesic monitoring, continuing education and, to a limited extent, small mammals. The veterinary surgeons considered that pain was a consequence of all the surgical procedures specified. Analgesics were administered by 94 per cent of them to cats undergoing orthopaedic surgery, by 72 per cent for the repair of a ruptured diaphragm, by 56 per cent for laparotomy, by 26 per cent for ovariohysterectomy, by 16 per cent for castration and by 39 per cent for dental work. Women and more recent graduates assigned higher pain scores to the procedures, and there was a significant correlation between the pain score and the number of veterinary surgeons who routinely gave analgesic, resulting in women and more recent graduates being more likely to treat the pain with analgesics. The majority of the veterinarians performed surgery on small mammals, but on average only 22 per cent gave perioperative analgesics, and the number giving analgesics varied with the species of small mammal. The perioperative monitoring of animals was largely delegated to nursing staff
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Background: Ear tattooing is a routine procedure performed on laboratory, commercial and companion rabbits for the purpose of identification. Although this procedure is potentially painful, it is usually performed without the provision of analgesia, so compromising animal welfare. Furthermore, current means to assess pain in rabbits are poor and more reliable methods are required. The objectives of this study were to assess the physiological and behavioural effects of ear tattooing on rabbits, evaluate the analgesic efficacy of topical local anaesthetic cream application prior to this procedure, and to develop a scale to assess pain in rabbits based on changes in facial expression. Methodology/principal findings: In a crossover study, eight New Zealand White rabbits each underwent four different treatments of actual or sham ear tattooing, with and without prior application of a topical local anaesthetic (lidocaine/prilocaine). Changes in immediate behaviour, heart rate, arterial blood pressure, serum corticosterone concentrations, facial expression and home pen behaviours were assessed. Changes in facial expression were examined to develop the Rabbit Grimace Scale in order to assess acute pain. Tattooing without EMLA cream resulted in significantly greater struggling behaviour and vocalisation, greater facial expression scores of pain, higher peak heart rate, as well as higher systolic and mean arterial blood pressure compared to all other treatments. Physiological and behavioural changes following tattooing with EMLA cream were similar to those in animals receiving sham tattoos with or without EMLA cream. Behavioural changes 1 hour post-treatment were minimal with no pain behaviours identifiable in any group. Serum corticosterone responses did not differ between sham and tattoo treatments. Conclusions: Ear tattooing causes transient and potentially severe pain in rabbits, which is almost completely prevented by prior application of local anaesthetic cream. The Rabbit Grimace Scale developed appears to be a reliable and accurate way to assess acute pain in rabbits.
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Fiji is a distribution of the popular open-source software ImageJ focused on biological-image analysis. Fiji uses modern software engineering practices to combine powerful software libraries with a broad range of scripting languages to enable rapid prototyping of image-processing algorithms. Fiji facilitates the transformation of new algorithms into ImageJ plugins that can be shared with end users through an integrated update system. We propose Fiji as a platform for productive collaboration between computer science and biology research communities.
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Many pain assessment tools for preschool and school-aged children are based on facial expressions of pain. Despite broad use, their metrics are not rooted in the anatomic display of the facial pain expression. We aim to describe quantitatively the patterns of initiation and maintenance of the infant pain expression across an expressive cycle. We evaluated the trajectory of the pain expression of three newborns with the most intense facial display among 63 infants receiving a painful stimulus. A modified "point-pair" system was used to measure movement in key areas across the face by analyzing still pictures from video recording the procedure. Point-pairs were combined into "upper face" and "lower face" variables; duration and intensity of expression were standardized. Intensity and duration of expression varied among infants. Upper and lower face movement rose and overlapped in intensity about 30% into the expression. The expression reached plateau without major change for the duration of the expressive cycle. We conclude that there appears to be a shared pattern in the dynamic trajectory of the pain display among infants expressing extreme intensity. We speculate that these patterns are important in the communication of pain, and their incorporation in facial pain scales may improve current metrics.
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We recently demonstrated the utility of quantifying spontaneous pain in mice via the blinded coding of facial expressions. As the majority of preclinical pain research is in fact performed in the laboratory rat, we attempted to modify the scale for use in this species. We present herein the Rat Grimace Scale, and show its reliability, accuracy, and ability to quantify the time course of spontaneous pain in the intraplantar complete Freund's adjuvant, intraarticular kaolin-carrageenan, and laparotomy (post-operative pain) assays. The scale's ability to demonstrate the dose-dependent analgesic efficacy of morphine is also shown. In addition, we have developed software, Rodent Face Finder®, which successfully automates the most labor-intensive step in the process. Given the known mechanistic dissociations between spontaneous and evoked pain, and the primacy of the former as a clinical problem, we believe that widespread adoption of spontaneous pain measures such as the Rat Grimace Scale might lead to more successful translation of basic science findings into clinical application.
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Newborns and infants are often exposed to painful procedures during hospitalization. Several different scales have been validated to assess pain in specific populations of pediatric patients, but no single scale can easily and accurately assess pain in all newborns and infants regardless of gestational age and disease state. A new pain scale was developed, the COVERS scale, which incorporates 6 physiological and behavioral measures for scoring. Newborns admitted to the Neonatal Intensive Care Unit or Well Baby Nursery were evaluated for pain/discomfort during two procedures, a heel prick and a diaper change. Pain was assessed using indicators from three previously established scales (CRIES, the Premature Infant Pain Profile, and the Neonatal Infant Pain Scale), as well as the COVERS Scale, depending upon gestational age. Premature infant testing resulted in similar pain assessments using the COVERS and PIPP scales with an r = 0.84. For the full-term infants, the COVERS scale and NIPS scale resulted in similar pain assessments with an r = 0.95. The COVERS scale is a valid pain scale that can be used in the clinical setting to assess pain in newborns and infants and is universally applicable to all neonates, regardless of their age or physiological state.
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Facial expression is widely used as a measure of pain in infants; whether nonhuman animals display such pain expressions has never been systematically assessed. We developed the mouse grimace scale (MGS), a standardized behavioral coding system with high accuracy and reliability; assays involving noxious stimuli of moderate duration are accompanied by facial expressions of pain. This measure of spontaneously emitted pain may provide insight into the subjective pain experience of mice.
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The primal face of pain (PFP) is postulated to be a common and universal facial expression to pain, hardwired and present at birth. We evaluated its presence by applying a computer-based methodology consisting of "point-pair" comparisons captured from video to measure facial movement in the pain expression by way of change across two images: one image before and one image after a painful stimulus (heel-stick). Similarity of facial expression was analyzed in a sample of 57 neonates representing both sexes and 3 ethnic backgrounds (African American, Caucasian and Hispanic/Latino) while controlling for these extraneous and potentially modulating factors: feeding type (bottle, breast, or both), behavioral state (awake or asleep), and use of epidural and/or other perinatal anesthesia. The PFP is consistent with previous reports of expression of pain in neonates and is characterized by opening of the mouth, drawing in of the brows, and closing of the eyes. Although facial expression was not identical across or among groups, our analyses showed no particular clustering or unique display by sex, or ethnicity. The clinical significance of this commonality of pain display, and of the origin of its potential individual variation begs further evaluation.
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Forty dogs undergoing a variety of orthopaedic surgical procedures were randomly assigned to one of two analgesic protocols, receiving either pethidine at 2 mg/kg pre-operatively and 3 mg/kg postoperatively, or carprofen, a new non-steroidal anti-inflammatory drug at 4 mg/kg pre-operatively. Analgesia and sedation were assessed after the operations under double blind conditions using a discontinuous scoring system and a visual analogue scale. There was good agreement between the two scoring systems, and a statistical analysis of the visual analogue scores showed that carprofen provided slightly better pain relief than pethidine and produced less sedation. Carprofen provided good analgesia during the 18 hours the dogs were in hospital and no adverse side effects were observed.
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In March 1996, a questionnaire was sent to 2000 veterinary surgeons, primarily involved in small animal practice, to assess their attitudes to perioperative analgesic therapy in dogs, cats and other small mammals. This paper is concerned only with the data relating to dogs. The veterinary surgeons considered that pain was a consequence of all the surgical procedures specified, but there were differences in their treatment of pain. Some veterinarians considered that a degree of pain was necessary postoperatively to prevent excessive activity. In general, women and more recent graduates assigned higher pain scores to the procedures and were more likely to treat the pain with analgesics. A significant number of veterinarians consider the use of opiates or non-steroidal anti-inflammatory drugs before surgical procedures, but relatively few appear to use combinations of different classes of analgesics either before or after operations.
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This study addresses development and validation of a composite multifactorial pain scale (CPS) in an experimental equine model of acute orthopaedic pain. Eighteen horses were allocated to control (sedation with/without epidural analgesia - mixture of morphine, ropivacaine, detomidine and ketamine) and experimental groups: amphotericin-B injection in the tarsocrural joint induced pain and analgesia was either i.v. phenylbutazone administered post-induction of synovitis, or pre-emptive epidural mixture, or a pre-emptive combination of the 2. Inter- and intra-observer reproducibility was good (0.8<K<1). The key specific and sensitive behavioural indices were response to palpation of the painful area, posture, and, of lesser value, pawing on the floor, kicking at abdomen and head movement. Of particular interest was the statistical correlation observed between the CPS and both non-invasive blood pressure (P<0.0001) and blood cortisol (P<0.002). This study established the value of some behavioural and physiological criteria in determining equine orthopaedic pain intensity and clearly demonstrated that pre-emptive, multimodal analgesia provided better management than the two other protocols tested.
Article
To develop a composite measure pain scale tool to assess acute pain in cats and derive an intervention score. To develop the prototype composite measure pain scale-feline, words describing painful cats were collected, grouped into behavioural categories and ranked. To assess prototype validity two observers independently assigned composite measure pain scale-feline and numerical rating scale scores to 25 hospitalised cats before and after analgesic treatment. Following interim analysis the prototype was revised (revised composite measure pain scale-feline). To determine intervention score, two observers independently assigned revised composite measure pain scale-feline and numerical rating scale scores to 116 cats. A further observer, a veterinarian, stated whether analgesia was necessary. Mean ± sd decrease in revised composite measure pain scale-feline and numerical rating scale scores following analgesia were 2 · 4 ± 2 · 87 and 1 · 9 ± 2 · 34, respectively (95% confidence interval for mean change in revised composite measure pain scale-feline between 1 · 21 and 3 · 6). Changes in revised composite measure pain scale-feline and numerical rating scale were significantly correlated (r = 0 · 8) (P < 0001). Intervention level score of ≥4/16 was derived for revised composite measure pain scale-feline (26 · 7% misclassification) and ≥3/10 for numerical rating scale (14 · 5% misclassification). A valid instrument with a recommended analgesic intervention level has been developed to assess acute clinical pain in cats that should be readily applicable in practice. © 2014 British Small Animal Veterinary Association.
Article
Pain expression in neonates instigated by heel-lance for blood sampling purposes was systematically described using measures of facial expression and cry and compared across sleep/waking states and sex. From gate-control theory it was hypothesized that pain behavior would vary with the ongoing functional state of the infant, rather than solely reflecting tissue insult. Awake-alert but inactive infants responded with the most facial activity, consistent with current views that infants in this state are most receptive to environmental stimulation. Infants in quiet sleep showed the least facial reaction and the longest latency to cry. Fundamental frequency of cry was not related to sleep/waking state. This suggested that findings from the cry literature on qualities of pain cry as a reflection of nervous system ‘stress’, in unwell newborns, do not generalize directly to healthy infants as a function of state. Sex differences were apparent in speed of response, with boys showing shorter time to cry and to display facial action following heel-lance. The findings of facial action variation across sleep/waking state were interpreted as indicating that the biological and behavioral context of pain events affects behavioral expression, even at the earliest time developmentally, before the opportunity for learned response patterns occurs. Issues raised by the study include the importance of using measurement techniques which are independent of preconceived categories of affective response.
Article
Numerous faces scales have been developed for the measurement of pain intensity in children. It remains unclear whether any one of the faces scales is better for a particular purpose with regard to validity, reliability, feasibility, and preference. To summarize and systematically review faces pain scales most commonly used to obtain self-report of pain intensity in children for evaluation of reliability and validity and to compare the scales for preference and utility. Five major electronic databases were systematically searched for studies that used a faces scale for the self-report measurement of pain intensity in children. Fourteen faces pain scales were identified, of which 4 have undergone extensive psychometric testing: Faces Pain Scale (FPS) (scored 0-6); Faces Pain Scale-Revised (FPS-R) (0-10); Oucher pain scale (0-10); and Wong-Baker Faces Pain Rating Scale (WBFPRS) (0-10). These 4 scales were included in the review. Studies were classified by using psychometric criteria, including construct validity, reliability, and responsiveness, that were established a priori. From a total of 276 articles retrieved, 182 were screened for psychometric evaluation, and 127 were included. All 4 faces pain scales were found to be adequately supported by psychometric data. When given a choice between faces scales, children preferred the WBFPRS. Confounding of pain intensity with affect caused by use of smiling and crying anchor faces is a disadvantage of the WBFPRS. For clinical use, we found no grounds to switch from 1 faces scale to another when 1 of the scales is in use. For research use, the FPS-R has been recommended on the basis of utility and psychometric features. Data are sparse for children below the age of 5 years, and future research should focus on simplified measures, instructions, and anchors for these younger children.
Article
Evaluation of pain in neonates is difficult due to their limited means of communication. The aim was to determine whether behavioural reactions of cry and facial activity provoked by an invasive procedure could be discriminated from responses to non-invasive tactile events. Thirty-six healthy full-term infants (mean age 2.2 h) received 3 procedures in counterbalanced order: intramuscular injection, application of triple dye to the umbilical stub, and rubbing thigh with alcohol. Significant effects of procedure were found for total face activity and latency to face movement. A cluster of facial actions comprised of brow bulging, eyes squeezed shut, deepening of the naso-labial furrow and open mouth was associated most frequently with the invasive procedure. Comparisons between the 2 non-invasive procedures showed more facial activity to thigh swabbing and least to application of triple dye to the umbilical cord. Acoustic analysis of cry showed statistically significant differences across procedures only for latency to cry and cry duration for the group as a whole. However, babies who cried to two procedures showed higher pitch and greater intensity to the injection. There were no significant differences in melody, dysphonation, or jitter. Methodological difficulties for investigators in this area were examined, including criteria for the selection of cries for analysis, and the logical and statistical challenges of contrasting cries induced by different conditions when some babies do not always cry. It was concluded that facial expression, in combination with short latency to onset of cry and long duration of first cry cycle typifies reaction to acute invasive procedures.
Article
We have developed a neonatal pain assessment tool CRIES. The tool is a ten point scale similar to the APGAR score (Apgar 1953). It is an acronym of five physiological and behavioural variables previously shown to be associated with neonatal pain. C--Crying; R--Requires increased oxygen administration; I--Increased vital signs; E--Expression; S--Sleeplessness. We have tested CRIES for validity and reliability. This report is the result of that testing. We have found CRIES to be valid, reliable and well accepted by neonatal nurses.
Article
Pain assessment in neonates often presents problems. The problem of inadequate or inaccurate assessment is complicated by issues related to the nature, consistency, and variability of the infant's physiologic and behavioral responses; the reliability, validity, specificity, sensitivity, and practicality of existing neonatal pain measures or measurement approaches; ethical questions about pain research in infants; and uncertainty about the responsibilities of health care professionals in managing pain in clinical settings. Despite these many issues, neonates need to be comfortable and as free of pain as possible to grow and develop normally. Valid and reliable assessment of pain is the major prerequisite for attaining this goal. Issues embodied in neonatal pain responses, measurement, ethical, and clinical considerations are explored. Suggestions for resolving some of these problems are presented.
Article
Inadequate assessment of pain in premature infants is a persistent clinical problem. The objective of this research was to develop and validate a measure for assessing pain in premature infants that could be used by both clinicians and researchers. The Premature Infant Pain Profile (PIPP) was developed and validated using a prospective and retrospective design. Indicators of pain were identified from clinical experts and the literature. Indicators were retrospectively tested using four existing data sets. Infants of varying gestational ages undergoing different painful procedures from three different settings were utilized to develop and validate the measure. The largest data set (n = 124) was used to develop the PIPP. The development process included determining the factor structure of the data, developing indicators and indicator scales and establishing internal consistency. The remaining three data sets were utilized to establish beginning construct validity. The PIPP is a newly developed pain assessment measure for premature infants with beginning content and construct validity. The practicality and feasibility for using the PIPP in clinical practice will be determined in prospective research in the clinical setting.
Article
Assessment of infant pain is a pressing concern, especially within the context of neonatal intensive care where infants may be exposed to prolonged and repeated pain during lengthy hospitalization. In the present study the feasibility of carrying out the complete Neonatal Facial Coding System (NFCS) in real time at bedside, specifically reliability, construct and concurrent validity, was evaluated in a tertiary level Neonatal Intensive Care Unit (NICU). Heel lance was used as a model of procedural pain, and observed with n = 40 infants at 32 weeks gestational age. Infant sleep/wake state, NFCS facial activity and specific hand movements were coded during baseline, unwrap, swab, heel lance, squeezing and recovery events. Heart rate was recorded continuously and digitally sampled using a custom designed computer system. Repeated measures analysis of variance (ANOVA) showed statistically significant differences across events for facial activity (P < 0.0001) and heart rate (P < 0.0001). Planned comparisons showed facial activity unchanged during baseline, swab and unwrap, then increased significantly during heel lance (P < 0.0001), increased further during squeezing (P < 0.003), then decreased during recovery (P < 0.0001). Systematic shifts in sleep/wake state were apparent. Rise in facial activity was consistent with increased heart rate, except that facial activity more closely paralleled initiation of the invasive event. Thus facial display was more specific to tissue damage compared with heart rate. Inter-observer reliability was high. Construct validity of the NFCS at bedside was demonstrated as invasive procedures were distinguished from tactile. While bedside coding of behavior does not permit raters to be blind to events, mechanical recording of heart rate allowed for an independent source of concurrent validation for bedside application of the NFCS scale.
Article
The objectives of this study were to: (1). evaluate the validity of the Neonatal Facial Coding System (NFCS) for assessment of postoperative pain and (2). explore whether the number of NFCS facial actions could be reduced for assessing postoperative pain. Prospective, observational study. Thirty-seven children (0-18 months old) undergoing major abdominal or thoracic surgery. The outcome measures were the NFCS, COMFORT "behavior" scale, and a Visual Analog Scale (VAS), as well as heart rate, blood pressure, and catecholamine and morphine plasma concentrations. At 3-hour intervals during the first 24 hours after surgery, nurses recorded the children's heart rates and blood pressures and assigned COMFORT "behavior" and VAS scores. Simultaneously we videotaped the children's faces for NFCS coding. Plasma concentrations of catecholamine, morphine, and its metabolite M6G were determined just after surgery, and at 6, 12, and 24 hours postoperatively. All 10 NFCS items were combined into a single index of pain. This index was significantly associated with COMFORT "behavior" and VAS scores, and with heart rate and blood pressure, but not with catecholamine, morphine, or M6G plasma concentrations. Multidimensional scaling revealed that brow bulge, eye squeeze, nasolabial furrow, horizontal mouth stretch, and taut tongue could be combined into a reduced measure of pain. The remaining items were not interrelated. This reduced NFCS measure was also significantly associated with COMFORT "behavior" and VAS scores, and with heart rate and blood pressure, but not with the catecholamine, morphine, or M6G plasma concentrations. This study demonstrates that the NFCS is a reliable, feasible, and valid tool for assessing postoperative pain. The reduction of the NFCS to 5 items increases the specificity for pain assessment without reducing the sensitivity and validity for detecting changes in pain.
Development of behaviour-based mea-surement tool with defined intervention level for assessing acute pain in cats Development of the horse grimace scale (HGS) as a pain assessment tool in horses undergoing routine castration
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Calvo, G., Holden, E., Reid, J., et al. (2014) Development of behaviour-based mea-surement tool with defined intervention level for assessing acute pain in cats. Journal of Small Animal Practice 55, 622-629 Dalla Costa, E., Minero, M., Lebelt, D., et al. (2014) Development of the horse grimace scale (HGS) as a pain assessment tool in horses undergoing routine castration. PLoS One 9, 1-10
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British Small Animal Veterinary Association Bussières Development of a composite orthopaedic pain scale in horses
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Journal of Small Animal Practice • Vol 55 • December 2014 • © 2014 British Small Animal Veterinary Association Bussières, G., Jacques, C., Lainay, O., et al. (2008) Development of a composite orthopaedic pain scale in horses. Research in Veterinary Science 85, 294-306
The Expression of the Emotions in Man and Animals Pain expression in neonates: facial action and cry
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0: fully alert and able to stand and walk 1: alert, able to maintain sternal recumbency and walk but may be ataxic 2: drowsy, able to maintain sternal recumbency but unable to stand 3: fast asleep, unable to raise head Sedation Score
  • Sedation Scale
  • Modified From Lascelles Et
Facial expression in cats APPENDIX 2: SEDATION SCALE, MODIFIED FROM LASCELLES ET AL. (1994) 0: fully alert and able to stand and walk 1: alert, able to maintain sternal recumbency and walk but may be ataxic 2: drowsy, able to maintain sternal recumbency but unable to stand 3: fast asleep, unable to raise head Sedation Score...........
Current British veterinary attitudes to perioperative analgesia for cats and small mammals
  • Lascelles