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Abstract

Infrared thermography (IRT) has been used to assess the health of canines by measuring surface temperatures. However, little is known about the effect hair coat differences has on expected surface temperature in healthy canines under the influence of hair coat differences. The aim of this study was to identify the influence of coat characteristics in body surface temperature (BST) in canines (Canis lupus familiaris). To determine the changes in BST, an infrared thermal imaging camera (i.e. FLIR B400) was used. Thermal images of the left and right sides of privately-owned dogs (n = 50) were acquired. Each animal acclimated in an indoor environment away from direct sunlight (23 ± 2.0 °C) for 15 min, and images were taken at a distance 0.67 ± 0.24 m. Regions of interest (ROIs) of mean surface temperatures were examined across the lateral surface of each animal. No statistical differences were detected based on laterality (P = 0.08). Mean BSTs were categorized by each dog's hair coat type: short coat (SC), curly coat (CC), long coat (LC), and double coat (DC). These BSTs were then analyzed using two-way analysis of variance, or ANOVA, (Shapiro-Wilk) and pairwise comparison. SC animals had the highest BST (31.77 ± 0.19 °C; P < 0.001) whereas LC (28.14 ± 0.31 °C; P < 0.001) and DC animals (28.25 ± 0.23 °C; P < 0.001) were lower in BST. CC animals portrayed intermediate BST (29.85 ± 0.33 °C; P < 0.001). The Pearson correlation and one-way ANOVA between rectal temperature and BST and coat type were not statistically significant (r = −0.24 and P = 0.07, respectively). Results indicate that short-haired dogs exhibit a more drastic increase in BST (approximately 2 °C) in comparison to other dogs and this should be considered in future clinical applications.

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... In the previous chapter, it has been shown that the chosen area of interest can influence mean ST and that the type of coat plays a significant role in determining the correct thermal values in healthy canines (Kwon & Brundage, 2019). Based on these results, this chapter will be focusing on a more detailed quantitative analysis of the same regions. ...
... Similar findings were found when observing the torso and hindquarter as a whole (Kwon & Brundage, 2019). ...
... Like the main body region, the overall mean ST of the limbs in SC dogs were at least 2 °C warmer than other coat types (Kwon & Brundage, 2019 (2007) found that the stifle region has a higher mean ST to the regions distally on the hindlimb in Labrador Retrievers, which is a short-haired dog breed. Our results show that SC dogs showed a decrease in mean ST on the hindlimb distally from the stifle. ...
Thesis
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For approximately 40 years, animal thermography has grown due to its non-contact approach in observing the thermoregulatory patterns of various mammals. Extensive work has been done in understanding the thermal patterns in both human and equine thermography. However, less knowledge is available regarding canine thermography. Infrared thermography (IRT) is a non-contact technique that detects emitted radiation represented as surface temperature of the canine body. This study aimed to evaluate coat variation and analyzed how thermal patterns may differ in canines. A thermal imaging camera (FLIR B400) was used to capture thermal images of the full lateral sides of each canine (n = 50). Regions of interest (ROIs) were drawn across the torso, hindquarter, and limbs of each canine. Coat variation represented as short coat (SC), long coat (LC), curly coat (CC), and double coat (DC) have shown to be statistically significant (P < 0.001). Significant differences identified an ability of different coat types to influence thermal patterning as well as the overall surface temperature (ST) of canines. Short-coat breeds were approximately 2 °C warmer than other breeds. Mean surface temperatures (STs) decrease distally in the limbs. In general, ST decreased distally on the forelimbs and hindlimbs. Averages of the horizontal and vertical pattern exhibited the highest mean ST was at the most caudal and ventral portion of the torso; the highest mean ST was at the most cranial and ventral part of the hindquarters. When evaluating the surface temperature of canine bodies and limbs it is important to consider the effect of coat type and the changes in pattern moving horizontally and vertically across the main body region. http://hdl.handle.net/10211.3/210800
... Environmental conditions and coat length could probably account for these different findings. However, Kwon and Brundage (2019) examined short-coated and curly-coated dogs and reported a mean superficial body temperature greater than 29 °C, similar to our findings [25]. A difference in mean temperature value at T0 was found in our outcomes between curly-haired and short-haired dogs, but this difference was in agreement with the literature [25]. ...
... However, Kwon and Brundage (2019) examined short-coated and curly-coated dogs and reported a mean superficial body temperature greater than 29 °C, similar to our findings [25]. A difference in mean temperature value at T0 was found in our outcomes between curly-haired and short-haired dogs, but this difference was in agreement with the literature [25]. ...
... For this reason, steel tables or containment cages were avoided. As previously discussed, the coat has also been implicated as a cause of different interpretations of thermographic images [1,3,4,17,25]. In our experience, we did not find any difficulty during the interpretation and analysis of images for curly-haired dogs with reduced coat, but we did not examine long-haired dogs. ...
Article
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Thermography is a non-invasive diagnostic method commonly used to monitor changes of the body surface temperature potentially induced by different conditions such as fever, inflammation, trauma, or changes of tissue perfusion. Capacitive-resistive diathermy therapy (such as energy transfer capacitive and resistive—Tecar) is commonly used in rehabilitation due to its diathemic effect secondary to blood circulation increase that could accelerate the healing process. The aim of this study was to monitor by thermal camera the diathermic effects induced by Tecar on the surface of the region of application. The investigation was conducted on six dogs referred for Tecar therapy to treat muscle contractures (three dogs) or osteoarthritis (three dogs). Eleven anatomical treated regions were recorded. Thermographic images and relative measurements were obtained by each region immediately before (T0), at conclusion (T1), and sixty seconds after the Tecar application (T2). Data were recorded and statistically analyzed. A comparison of temperature differences (maximum, minimum and mean values) between T0 and T1, T0 and T2, and T1 and T2 was performed by ANOVA test with Bonferroni post hoc (p ≤ 0.05). Statistically significant differences were detected for mean temperature between T0 (32.42 ± 1.57 °C) and T1 (33.36 ± 1.17 °C) (p = 0.040) and between T1 and T2 (32.83 ± 1.31 °C) (p = 0.031). Furthermore, there was no significant difference between the mean temperature at T0 and T2, demonstrating that superficial diathermic effect exhausted within 60 s.
... Reproducible thermal body patterns have been identified in healthy canines [14] with symmetrical distribution between both sides of the body [15]. The warmest body surface temperatures have been reported at the torso and hindquarters, with surface temperature distribution across the limbs giving rise to proximal areas warmer compared with distal parts [16]. Studies based on different dog breeds concluded that the biggest impact on body surface temperature was the type and color of hair coat [6,14,16]. ...
... The warmest body surface temperatures have been reported at the torso and hindquarters, with surface temperature distribution across the limbs giving rise to proximal areas warmer compared with distal parts [16]. Studies based on different dog breeds concluded that the biggest impact on body surface temperature was the type and color of hair coat [6,14,16]. ...
... The hypothesis of the study was that body surface temperature in specific body regions increases in response to high-speed exercise on the treadmill. The study was based exclusively on the Beagle breed, commonly used in canine thermography studies [14], which presents short, uniform, and straight hair, conducting heat more readily from the skin compared with hair that lays flat against the surface of the body [16]. ...
Article
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Evaluation of body surface temperature change in response to exercise is important for monitoring physiological status. The aim of the study was to assess the influence of high-speed treadmill exercise on body surface temperature using infrared thermography (IRT) in selected body regions of healthy Beagle dogs, taking into account gait and recovery time. Thermographic images of the dogs were taken before exercise (BE), after walk (AW), after trot (AT), after canter (AC), just after second walk (JAE), 5 min after exercise (5 AE), 15 min after exercise (15 AE), 30 min after exercise (30 AE), 45 min after exercise (45 AE), and 120 min after exercise (120 AE). Body surface temperature was measured at the neck, shoulder, upper forearm, back, chest, croup, and thigh. Statistical analysis indicated the highest temperature at the upper forearm, shoulder, and thigh, and the lowest on the croup, back, and neck. The peak values of surface temperature in all ROIs were at AC and JAE and the lowest at 120 AE. The study demonstrated that body surface temperature was influenced by high-speed physical exercise on a treadmill and IRT was a viable imaging modality that provided temperature data from specific body regions. The proximal forelimb and hindlimb were the most influenced by exercise.
... Measurement accuracy is greatly influenced by several factors, such as environmental conditions (temperature and humidity) and the location of measurements [3,14]. Moreover, the significant variation in signalments (body condition score [BCS], coat type, breed, and body size) in dogs compared to livestock can lead to inaccurate measurements [3,14,16]. A significant correlation between rectal body and infrared ST in dogs has been reported in several studies, although with considerable variations [3,14]. ...
... Hair, as an insulator, prevents heat loss from animals [19], with long hair providing better protection. In a previous study, the highest ST was observed in the lateral area of short-coat dogs, followed by curly ones and double coat ones [16]. Therefore, the accuracy of the prediction equation based on a long hair coat was higher than that of the equation based on short hair. ...
Article
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Background and aim: Generally, rectal body temperature (BTrectum) is used to prefer as core body temperature in dogs. However, this procedure is time- and labor-consuming with stress induction. Therefore, infrared auricular temperature (BTear) and surface temperature (ST) could be applied to estimate BTrectum. This study aimed to estimate BTrectum from BTear or ST in various areas and determined the factors that influenced the accuracy of prediction equations. Materials and methods: Under controlled temperature (n=197) and ambient temperature (n=183), the parameters BTrectum, BTear, and ST at internal pinna, auricular canal, lateral aspect of shoulder, hip, axillary area, inguinal area, footpad, and anal area (STrectum) were measured. In addition, temperature and humidity levels of the surrounding environment were recorded. The correlation between each measurement technique was calculated. The BTrectum prediction equation was created using all measured data and several influencing factors (environmental condition, size, coat type, and body condition score [BCS]). Results: The highest correlation with BTrectum was observed for BTear (r=0.61, p<0.01), which was similar to STrectum (r=0.61, p<0.01). Based on multiple linear regression model results using BTrectum as the dependent variable, BTear or STrectum were first selected as independent variables in all estimation equations. Ambient temperatures (R2=0.397), small breed (R2=0.582), long hair (R2=0.418), and/or a BCS of 2 (R2=0.557) provided the highest coefficients of determination of the prediction equation. Conclusion: The most appropriate predictors for estimating BTrectum were STrectum and BTear, which were impacted by the dog's signalments and the environment. To obtain satisfactory outcomes, the equation must be selected depending on the dog's signalments and the environmental conditions. However, based on the findings of this investigation, the accuracy remains low in several equations, and further studies are needed to improve the accuracy of the equation, mainly by increasing the sample size and developing a specific equation for each dog's signaling and environmental condition.
... Furthermore, multiple studies investigated how individual animal factors can affect IRT results in healthy animals (Berry et al., 2003;Petr and Ivana, 2012;Purohit et al., 2012;Rekant et al., 2016;Turner, 2018). Therefore, BST is reported to be influenced by the coat type, the colour of the skin, the haired and non-haired skin (Kwon and Brundage, 2019;Subedi et al., 2014). Alternatively, it has been noted by two canine studies that haircutting is not necessary to produce accurate thermal patterns in both healthy and injured dogs (Infernuso et al., 2010). ...
... In small animal medicine, IRT is reported to be sensitive in detecting abnormal thermal patterns related to various clinical conditions, such as neoplasia, ophthalmologic diseases, behaviour and welfare, as well as to identify the localization of orthopaedic and neurological conditions (Elias et al., 2021;Gorre et al., 2020;Kwon and Brundage, 2019;Luzi et al., 2014a;Rekant et al., 2016;Travain et al., 2015). A recent study reported the sensitivity of IRT in localizing the injured area in chondrodistrophic dogs with thoracic disc herniation, comparing with the magnetic resonance imaging results and surgical findings (Grossbard et al., 2014). ...
Article
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The aim this study was to evaluate variation in body surface temperature (BST) in healthy and spinal cord injured (SCI) dogs, and to outline temperature variation at rest (T0), during (T1) and after (T2) water-treadmill physiotherapy sessions in SCI using infrared thermography (IRT). Sixty-seven dogs of different sex, breed, body weight and age were enrolled: 14 healthy dogs and 53 dogs affected by disc pathologies. The study examined three regions of interest (ROIs): the total image of the spine (IMAGE), the spinal cord area from 1st thoracic vertebra to the last lumbar vertebra (AR01) and the surgery wound or spinal cord lesion area (AR02). Significant BST variations between healthy and SCI were reported in T°max and T°max-min (ΔT) values in IMAGE (P < 0.05). In SCI group, AR01 and AR02 assessment showed an increase in temperature ate the sited of the injured area and adjacent body structures. In SCI, a significant effect of water-treadmill exercise in AR01 and AR02 was reported. In fact, both AR01 and AR02 reported higher BST (T°max, T°mean, T°min and ΔT) during the physical exercise (T1), representing the response to physical activity of the spine vascularization, muscles and column contiguous tissues. Furthermore, in T2, the same areas reported a significant lower BST (T°max, T°mean, and ΔT), related to a decrease in tissue inflammation on the target area of the water treadmill physiotherapy. This study highlights how IRT can detect BST variations associated with injured areas. In addition, IRT revealed a positive effect of water-treadmill exercise on the injured spinal cord areas, thus it could be a viable non-invasive and rapid method to support both clinical examination and assessment of the effectiveness of medical treatment in SCI.
... These findings demonstrate IRT's usefulness for the early detection of inflammatory conditions [11], though its sensitivity is still in doubt because of potential biological and environmental influences [12]. This has been evidenced in appendicular regions, where sensitivity and effectiveness can be affected, for example, by the length or type of an animal's hair or fur [13]. ...
... Those authors found no differences in the dogs' facial expressions during their assessment of this anatomical region but did observe that the temperature was 3 • C higher in the dogs with short hair than those with long hair. This observation was reaffirmed by Kwon et al. [13] in their evaluation of the influence of the characteristics of animals' hair on the body surface, using 50 dogs acclimated to solar light for 15 min. They later obtained images of the lateral face of the femoral region and determined that the animals with a long, double coat of hair had lower temperatures (28.14 ± 0.31 • C and 28.25 ± 0.23 • C) than those that had short hair (31.77 ± 0.19 • C). ...
Article
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Infrared thermography (IRT) has been proposed as a method for clinical research to detect local inflammatory processes, wounds, neoplasms, pain, and neuropathies. However, evidence of the effectiveness of the thermal windows used in dogs and cats is discrepant. This review aims to analyze and discuss the usefulness of IRT in diverse body regions in household animals (pets) related to recent scientific evidence on the use of the facial, body, and appendicular thermal windows. IRT is a diagnostic method that evaluates thermal and circulatory changes under different clinical conditions. For the face, structures such as the lacrimal caruncle, ocular area, and pinna are sensitive to assessments of stress degrees, but only the ocular window has been validated in felines. The usefulness of body and appendicular thermal windows has not been conclusively demonstrated because evidence indicates that biological and environmental factors may strongly influence thermal responses in those body regions. The above has led to proposals to evaluate specific muscles that receive high circulation, such as the bicepsfemoris and gracilis. The neck area, perivulvar, and perianal regions may also prove to be useful thermal windows, but their degree of statistical reliability must be established. In conclusion, IRT is a non-invasive technique that can be used to diagnose inflammatory and neoplastic conditions early. However, additional research is required to establish the sensitivity and specificity of these thermal windows and validate their clinical use in dogs and cats.
... The animals with short fur presented a higher temperature (31.3 • C) than the dogs with long fur (28.3 • C) and the double layer (28.2 • C), while those with curly hair had an intermediate temperature (29.8 • C). This suggests that animals with a layer of short hair tend to present a higher surface temperature increase than those with a layer of long hair [115]. These differences are presented in Figure 6. ...
... In the case of the dogs being under direct solar radiation, the situation could be inverse, depending on the thickness and color of the fur. Being darker will determine more significant absorbance and minor transmittance [115]. ...
Article
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The objective of this review is to describe and analyze the effect of feathers, hair, and glabrous (hairless) skin on the thermoregulation of domestic and endotherm animals, especially concerning the uses and scope of infrared thermography (IRT), scientific findings on heat and cold stress, and differences among species of domestic animals. Clinical medicine considers thermoregulation a mechanism that allows animals to adapt to varying thermal environmental conditions, a process in which the presence of feathers, hair, or glabrous skin influences heat loss or heat retention, respectively, under hot and cold environmental conditions. Evaluating body temperature provides vital information on an individual’s physiological state and health status since variations in euthermia maintenance in vertebrates reflect a significant cellular metabolism deviation that needs to be assessed and quantified. IRT is a non-invasive tool for evaluating thermal responses under thermal stress conditions in animals, where the presence or absence of feathers, hair, and glabrous skin can affect readings and the differences detected. Therefore, anatomical regions, the characteristics of feathers, hair, glabrous skin such as structure, length, color, and extension, and strategies for dissipating or retaining heat together constitute a broad area of opportunity for future research into the phenomena of dermal thermoregulation in domestic species.
... Nonetheless, exposing the dogs to HA/LR did not significantly increase their RT, since they can dissipate approximately 70% of their total body heat through radiation and convection from body surfaces, which is conveniently effective at LR [21]. Animal breed, coat type/length, and coat color influence canine temperature [22]; however, in this study, the same group of dogs served as both the control and test animals, thereby eliminating these effects on their temperature. ...
Article
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Background and Aim: Heat stress is a major challenge for animals, impairing their welfare and performance. This study aimed to determine the effect of heat stress on the vital and hematobiochemical parameters of healthy dogs. Materials and Methods: The experimental subjects comprised 10 dogs, encompassing seven males and three non-pregnant females between 2 and 3 years of age. Ambient temperature (AT) and relative humidity (RH) were recorded 2 hourly during the day and the temperature humidity index was calculated. Vital parameters [i.e., rectal temperature (RT), respiratory rate, and heart rate (HR)] were assessed and blood was collected from each dog daily for hematobiochemical analysis. Results: The RT (38.5±0.2°C) of dogs exposed to high AT and high RH (HA/HR) conditions was significantly (p<0.05) higher than that of dogs exposed to HA and low RH (LR) conditions (37.2±0.11°C). Under HA/HR conditions, packed cell volume, hemoglobin concentrations, and white blood cell counts were significantly lower than those of the same dogs exposed to HA/LR conditions. Conversely, under HA/HR conditions, the lymphocyte, monocyte, eosinophil, alanine aminotransferase, aspartate aminotransferase, and cortisol values were significantly higher (p<0.05) than the values obtained in dogs exposed to HA/LR conditions. Meanwhile, the alkaline phosphatase, urea, and glucose levels were significantly lower (p<0.05) in dogs exposed to HA/HR conditions. Conclusion: The exposure of healthy dogs to HA/HR conditions induced heat stress, which may have an adverse effect on their immune status, thereby affecting their health and welfare.
... The breed of the canine can also cause more heat loss due to their lack of fat and thin fur. It is thought that canines with longer fur tend to have a cooler surface temperature, due to the insulation of the coat (Kwon and Brundage, 2019). The thermal cameras showed that the canines did not suffer from severe hyperthermia after the races, which indicate that the intrinsic cooling system is effective (Vainionpaa et al., 2012). ...
Article
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Body temperature is an important component in the diagnoses and treatment of disease in canines. Rectal temperature remains the standard of obtaining temperature within the clinical setting, but there are many drawbacks with this method, including time, access, animal stress and safety concerns. Interest in using infra-red thermometry in canines to obtain body temperature has grown as animal scientists and veterinarians search for non-invasive and non-contact methods and locations of obtaining canine temperatures. Here we review evidence on axillary, auricular, and ocular region canine thermometry and the degree to which measurements in these locations are representative of rectal temperature values. Instrumentation refinement and development, as well as morphologic differences, play an important role in the potential correlation between rectal temperature and these other locations. These caveats have yet to be fully addressed in the literature, limiting the options for those seeking alternatives to rectal thermometry.
... Selection of dogs with different coat lengths and body structure may have yielded different results. However, this Staffordshire terrier mixes were chosen in this study for the short coat characteristic of the breed thereby decreasing temperature variance noted in previous studies secondary to coat length (13,44). In addition, coat color was not consistent; however, this has not shown to affect thermal images (45). ...
Article
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Objective: To evaluate changes in superficial temperature of hindlimb muscles before and after a 6-min walk in healthy dogs. Methods: Two infrared thermographic images were captured of the proximal and distal hindlimbs of 11 healthy dogs before and after a 6-min walk. Orthopedic exam and objective gait analysis confirmed the healthy status of study subjects. Superficial temperatures of the gastrocnemius, biceps femoris, and gracilis were assessed. Analysis of images was performed using 2 different methods of region of interest (ROI) selection. ROI were selected first using one point (single pixel) in the muscle and then separately by selecting a line (LN) corresponding to many points of each muscle belly from which an average was taken. P < 0.05 was considered significant. Results: There was no significant change in temperature using point ROI before and after 6 min of walking of the gastrocnemius, gracilis, and biceps femoris muscles (p = 0.273, p = 0.349, p = 0.351, respectively). Using linear ROI, both biceps femoris and gracilis muscles exhibited significant increases in temperature (p < 0.0001, p = 0.032, respectively). There was no significant increase in temperature of gastrocnemius muscle for both point and linear ROI selection (p = 0.273, p = 0.448, respectively). The right biceps femoris temperatures were higher compared to left biceps femoris using the linear ROI before and after walks (p < 0.0001). The overall (left and right limbs pooled) standard deviation of point selected values were greater than LN selected values of the biceps femoris (1.35 and 1.11) and gastrocnemius (1.51 and 1.23). In contrast, standard deviation for the gracilis measurements were decreased using point selection vs. LN selection (1.09 and 1.3). Conclusions: The biceps femoris and gracilis muscles demonstrated significant increases in surface temperature after 6 min of walking using the linear method of ROI. Measurement of numerous points along the entire length of the biceps femoris and gastrocnemius muscles may provide a more accurate assessment of the increased vascularity within the tissues resulting from work compared to single point selection. Clinical Significance: Prior activity and ROI selection method should be considered when interpreting thermography results.
... It is a non-invasive and safe method for detecting changes in surface temperature [1][2][3]. In dogs, thermography is primarily used to identify inflammation, determine stress, or assess diseases that have thermal effects [4,5]. ...
Article
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In humans, radiation induces dilation of capillaries and inflammatory reactions to raise skin temperature. Thermography is used to detect abnormalities after radiation therapy (RT). However, in veterinary nursing, objective evaluation of the condition of dogs after RT using thermography has not been reported. We investigated the nasal irradiation temperature, behavioral changes, and post-irradiation pain scores in a dog receiving RT for intranasal tumors. The temperature of the nasal planum gradually increased after irradiation, reaching a significantly higher value at 120–240 min. The highest temperature was 42.3 °C and the average temperature increased by 4.4 °C. Behavioral analysis pre- and post-RT did not vary significantly. Post-RT pain levels evaluated by the pain scale ranged from 0 to 1 throughout. No veterinary treatment was provided. In humans, increased skin temperature after radiation causes psychological stress, i.e., pain and discomfort, but no such behavioral changes were observed in this case. Given individual differences in stress-related behaviors, such as pain and discomfort, assessing a dog’s painfulness using only subjective methods, such as appearance and behavioral evaluation, is limited. We used thermography to assess changes in conditions not detectable by routine monitoring alone. This method is non-invasive, objective, and indispensable for providing appropriate care.
... In both studies, increased body condition score had a negative correlation coefficient. Surprisingly, the hairiness correlation was not consistent (positive vs. negative), which could be a consequence of different coat types (Kwon and Brundage, 2019) or ambient temperatures affecting the insulation function of the coat. ...
Article
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Because dogs tolerate conventional rectal temperature measurements poorly, a calibrated infrared thermometer was tested for assessing canine body surface temperature. Body surface temperature of 217 dogs was estimated on various sites (digit, snout, axilla, eye, gum, inguinal region, and anal verge). Having rectal temperature as the gold standard, temperature difference, Spearman's correlation coefficient, hyperthermia and hypothermia detection sensitivity and specificity, and stress response score was calculated for each measurement site. Although the canine body surface temperature was considerably lower than the rectal temperature, there was a moderate correlation between both temperatures. Spearman's coefficients were 0.60 (p < 0.001) for the inguinal region with a single operator and 0.50 (p < 0.001) for the gum with multiple operators. Measurement site on the gum additionally guaranteed hyperthermia detection sensitivity and specificity up to 90.0% (95% CI: [66.7 100]) and 78.6% (95% CI: [71.6 85.2]), respectively. Measurements with the infrared thermometer provoked a statistically significant lower stress response (mean stress scores between 1.89 and 2.48/5) compared to the contact rectal measurements (stress score of 3.06/5). To conclude, the correct body surface temperature measurement should include a calibrated thermometer, reliable sampling, and the control of external factors such as ambient temperature influence. The transformation of body surface temperature to the recognized rectal temperature interval allows more straightforward data interpretation. The gum temperature exhibited the best clinical potential since the differences to rectal temperatures were below 1°C, and hyperthermia was detected with the sensitivity of up to 90%.
Article
Infrared thermography (IRT) is a tool that has been studied extensively in the experimental medical field as a method for assessing surface thermal responses under various conditions. These may involve local inflammatory processes resulting from surgical procedures, wounds, neoplasms, pathologies, painful events, or stressful states in animals. IRT measures changes in blood flow in surface blood capillaries and the resulting heat radiation. In the clinical field, thermography has been used as a support method for detecting painful conditions. However, some guidelines indicate that it could be applied for assessing and monitoring animals in rehabilitation to quantify objectively possible improvements in their quality of life. Similarly, it has been observed that IRT makes it possible to assess the degree of circulation in dermal tissue, suggesting that it could be used to determine the degree of damage in traumatized tissue in cases of thromboembolic diseases and burns. This would be useful to distinguish between damaged and healthy tissue and thus determine the optimal therapy for burn patients. This review aims to analyze scientific evidence on the clinical applications of IRT for detecting diseases and assessing painful conditions. A literature search on different databases was performed to recover articles related to the application of IRT as a complementary diagnostic tool, as well as its potential for assisting in rehabilitation, monitoring wounds, and evaluating body temperature in domestic animals.
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Core body temperature is indispensable in the assessment of the health status, as well as diagnosis and management of febrile conditions in patients. However, taking temperature in veterinary practice using conventional rectal thermometry could be challenging as most animals like horses often resent it. In this report, the reliability and accuracy of non-contact infrared thermometry in measuring temperature in horses is evaluated. Body surface infrared temperature readings of 40 horses were measured from three different sites (forehead, shoulder point, and anal verge regions) and compared with rectal thermometry as gold standard, the mean temperature differences, spearman’s correlation and reliability coefficients were calculated for each measurement site. Bland-Altman plot was used to assess the agreement and systematic differences between the non-contact infrared and rectal thermometry. All the analyses were evaluated at α0.05. The body surface temperatures were slightly lower and correlate poorly with rectal temperature (p>0.05). The Bland-Altman analysis showed low mean bias ± SD between infrared and rectal thermometry as forehead (1.06 ± 0.48℃), shoulder point (0.77 ± 0.48℃), and anal verge (0.32 ± 0.63℃); and high reliability with clinical potentials (Intraclass correlation and Cronbach's Alpha coefficients (r) ≥ 0.98). Based on this data, with the high consistency and agreement, as well as the low mean biases below 1oC, the non-contact infrared thermometry of the anal verge and shoulder point demonstrated the greatest clinical potentials as an alternative to rectal thermometry in horses.
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Although dark coat color in dogs has been theorized as a risk factor for heat injury, there is little evidence in the scientific literature to support that position. We utilized 16 non-conditioned Labradors (8 black and 8 yellow) in a three-phase test to examine effects of coat color on thermal status of the dog. Rectal, gastrointestinal (GI), and surface temperature using infrared thermography measured at the eye and abdomen, were measured along with respiration rate measured in breaths per minute (bpm), collected at three time points. Phase 1 (Baseline) – 30 minutes of crate rest in a climate-controlled room; Phase 2 (Walking in Sunlight) - 30-minute walk in an outdoor environment on a sunny day; and Phase 3 (Cooling) – 15 minutes of crate rest in climate-controlled room to determine post-exposure recovery temperatures. No effect of coat color was measured for rectal, gastrointestinal, surface temperature, or respiration rate (P > 0.05) in dogs following their 30-minute walk in sunlight. All temperatures measured increased similarly (rectal 1.86°C and 1.80°C; GI 1.92°C and 1.95°C; eye 2.8°C and 1.92°C; abdomen 2.91°C and 2.39°C) in black and yellow dogs respectively, following 30 in Sunlight (P > 0.05). Additionally, temperatures decreased in a similar fashion for both coat colors (rectal 0.84°C and 0.88°C; GI 1.48°C and 1.32°C; eye 1.49°C and 1.70°C; abdominal 1.75°C and 1.5°C) in black and yellow dogs respectively (P > 0.05) during Cooling. Respiration rate increased similarly for both coat colors, (147.2 bpm and 143.7 bpm for black and yellow respectively) when Baseline values were compared to Sunlight values and decreased similarly (28.8 bpm black; 60.2 bpm yellow after Cooling phase (P > 0.05). These novel data reveal a surprising lack of effect for black vs. yellow coat color on body temperature as measured by standard rectal thermometer, gastrointestinal thermistor, or infrared thermography in a population of Labrador retrievers.
Experiment Findings
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The COVID-19 pandemic has had a profound impact on the veterinary profession. Practices have struggled to maintain high-quality veterinary care while safeguarding the health and welfare of staff, patients and clients. Reducing hours of operation and triaging appointments based on the severity of a medical problem has significantly decreased the availability of clinic visits for patients with chronic but non-life-threatening conditions, often irritating the most loyal clientele. The primary aim of this multisite, prospective exploratory trial was to evaluate the efficacy of an in-home treatment protocol using a client-operated Class 1 hand-held laser device for the treatment of inflammatory conditions regularly seen in companion animal practice. A secondary aim of the study was to assess the interest level of clients in continued, albeit remote, care of their pets' medical conditions. N
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Osteoarthritis (OA) is the most common orthopedic condition in dogs, characterized as the chronic, painful end-point of a synovial joint with limited therapeutic options other than palliative pain control or surgical salvage. Since the 1970s, radiography has been the standard-of-care for the imaging diagnosis of OA, despite its known limitations. As newer technologies have been developed, the limits of detection have lowered, allowing for the identification of earlier stages of OA. Identification of OA at a stage where it is potentially reversible still remains elusive, however, yet there is hope that newer technologies may be able to close this gap. In this article, we review the changes in the imaging of canine OA over the past 50 years and give a speculative view on future innovations which may provide for earlier identification, with the ultimate goal of repositioning the limit of detection to cross the threshold of this potentially reversible disease.
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Infrared temperature measurement equipment (IRTME) is gaining popularity as a diagnostic tool for evaluating human and animal health. It has the prospect of reducing subject stress and disease spread by being implemented as an automatic surveillance system and by a quick assessment of skin temperatures without need for restraint or contact. This review evaluates studies and applications where IRTME has been used on pigs. These include investigations of relationships between skin, ambient and body temperatures and applications for detecting fever, inflammation, lesions, ovulation, and stress as well as for meat quality assessment. The best skin locations for high correlation between skin temperature and rectal temperature are most likely thermal windows such as ear base, eye region and udder. However, this may change with age, stressors, and biological state changes, for example, farrowing. The studies performed on pigs using IRTME have presented somewhat discrepant results, which could be caused by inadequate equipment, varying knowledge about reliable equipment operation, and site-specific factors not included in the assessment. Future focus areas in the field of IRTME are suggested for further development of new application areas and increased diagnostic value in the porcine and animal setting in general.
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The aims of this study were, first, to evaluate eye temperature (ET) with infrared thermography and heart rate (HR) to measure stress in horses during show jumping competitions and their relationship with competition results, and second, to evaluate the influence of different extrinsic and intrinsic factors of the horse on the stress measurements analysed. One hundred and seventy-three Spanish Sport Horses were analysed for ET and HR, and these measurements were taken 3 h before the competition, just after and 3 h after it. Two interval measurements were also assessed for each parameter. Positive significant correlations were found between ET and HR, measured before (r=0.23), just after competition (r=0.28) and for the later interval (r=0.26), whereas negative correlations with competition results were found only for ET when measured just after competing (r=-0.25). Two intrinsic factors (genetic line and age) and no extrinsic factors showed significant differences for ET, whereas one intrinsic factor (age) and two extrinsic factors (journey duration and number of training hours) showed significant differences for HR. The marginal means showed significantly higher ET values for the Anglo-Arab genetic line and for 5-year-old animals. HR values were significantly higher for 4-year-old animals, for horses which had travelled 4 to 6 h and for horses that had 3 to 6 h of daily training. This study suggests that, although ET and HR seemed to share a similar physiological basis, the factors that most influenced each parameter were different. Finally, ET seems to be a suitable tool for assessing stress during show jumping competitions in horses.
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Animals inheriting the slick hair gene have a short, sleek, and sometimes glossy coat. The objective of the present study was to determine whether slick-haired Holstein cows regulate body temperature more effectively than wild-type Holstein cows when exposed to an acute increase in heat stress. Lactating slick cows (n = 10) and wild-type cows (n = 10) were placed for 10 h in an indoor environment with a solid roof, fans, and evaporative cooling or in an outdoor environment with shade cloth and no fans or evaporative cooling. Cows were exposed to both environments in a single reversal design. Vaginal temperature, respiration rate, surface temperature, and sweating rate were measured at 1200, 1500, 1800, and 2100 h (replicate 1) or 1200 and 1500 h (replicate 2), and blood samples were collected for plasma cortisol concentration. Cows in the outdoor environment had higher vaginal and surface temperatures, respiration rates, and sweating rates than cows in the indoor environment. In both environments, slick-haired cows had lower vaginal temperatures (indoor: 39.0 vs. 39.4 degrees C; outdoor 39.6 vs. 40.2 degrees C; SEM = 0.07) and respiration rate (indoor: 67 vs. 79 breaths/ min; outdoor 97 vs. 107 breaths/min; SEM = 5.5) than wild-type cows and greater sweating rates in unclipped areas of skin (indoor: 57 vs. 43 g x h(-1)/m(2); outdoor 82 vs. 61 g x h(-1)/m(2); SEM = 8). Clipping the hair at the site of sweating measurement eliminated the difference between slick-haired and wild-type cows. Results indicate that slick-haired Holstein cows can regulate body temperature more effectively than wild-type cows during heat stress. One reason slick-haired animals are better able to regulate body temperature is increased sweating rate.
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A theory is developed to describe the transmission of thermal radiation through animal coats containing a uniform distribution of fibres. The theory predicts a dependence of the radiation energy emitted on both the coat structure and the direction of emission, and further suggests that directional radiometers (including thermographic devices) in general measure an effective coat temperature differing from that estimated from the net radiative energy balance.
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Research over the past 50 years has demonstrated the existence of circadian or daily rhythmicity in the body core temperature of a large number of mammalian species. However, previous studies have failed to identify daily rhythmicity of body temperature in dogs. We report here the successful recording of daily rhythms of rectal temperature in female Beagle dogs. The low robustness of the rhythms (41% of maximal robustness) and the small range of excursion (0.5 degrees C) are probably responsible for previous failures in detecting rhythmicity in dogs.
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The aim of this study was to investigate the reproducibility of skin surface infrared thermography (IRT) measurements and determine the factors influencing the variability of the measured values. While IRT has been widely utilized in different clinical conditions, there are few available data on the values of the skin temperature patterns of healthy subjects and their reproducibility. We recorded the whole body skin temperatures of sixteen healthy young men with two observers on two consecutive days. The results were compared using intra-class correlations analyses (ICC). The inter-examiner reproducibility of the IRT measurements was high: mean ICC 0.88 (0.73-0.99). The day-to-day stability of thermal patterns varied depending on the measured area: it was high in the core and poor in distal areas. The reproducibility of the side-to-side temperature differences (deltaT) was moderately good between the two observers (mean ICC 0.68) but it was reduced with time, especially in the extremities, mean ICC 0.4 (-0.01-0.83). The results suggest that the IRT technique may represent an objective quantifiable indicator of autonomic disturbances although there are considerable temporal variations in the measured values which are due to both technical factors such as equipment accuracy, measurement environment and technique, and physiological variability of the blood flow, and these factors should be taken into account.
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The hair follicle (HF) has a wide range of functions including thermoregulation, physical and immunological protection against external insults, sensory perception, social interactions, and camouflage. One of the most characteristic features of HFs is that they self-renew during hair cycle (HC) throughout the entire life of an individual to continuously produce new hair. HC disturbances are common in humans and comparable to some alopecic disorders in dogs. A normal HC is maintained by follicular stem cells (SCs), which are predominately found in an area known as the bulge. Due to similar morphological characteristics of the human and canine bulge area, the particularity of compound HFs in humans and dogs as well as similarities in follicular biomarker expression, the dog might be a promising model to study human HC and SC disorders. In this review, we give an overview of normal follicular anatomy, the HC, and follicular SCs and discuss the possible pathogenetic mechanisms of noninflammatory alopecia.
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This review of the use of thermographic technique in equines introduces the principles upon which infrared radiation and thermoregulatory physiology are based and describes the instrumentation used and its practical use. The advantage of this imaging technique is that it is a noninvasive thermographic examination, both from an operational (the animal and the operator) and health (no penetrating radiation is used) standpoint. Advantages and disadvantages of this technique, equine applications, and physiological assessments are discussed.
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The aim of the present study was to evaluate the modifications of some physiological parameters during moderate treadmill exercise in seven healthy Beagle dogs. All animals were submitted to treadmill exercise consisting of walking (15 min), trotting (20 min) and walking (10 min). At every step, rectal temperature (RT) was measured, and the mean heart rate (HR) was assessed. Venous blood samples were collected immediately before starting the treadmill exercise session (at rest), after the end of walking (15 min), trotting (20 min) and walking (10 min), and after 30 min of passive recovery. For immediate assessment of lactate and glucose concentration, blood was analyzed with portable blood lactate and blood glucose analyzers, respectively. Blood was also transferred into sterile glass tubes containing K(3)-ethylenediaminetetraacetic acid (K(3)-EDTA) for evaluation of red blood cells (RBC), white blood cells (WBC), platelets (PLT), hemoglobin (Hb), hematocrit (Hct), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC). One-way repeated measures analysis of variance (ANOVA) showed a significant effect of treadmill exercise (P<0.05) on RT, HR, lactate, glucose, RBC and Hct. Considering these significant variations, the knowledge of RT, HR, glucose and lactate concentrations, RBC, and Hct, the most suitable and sensitive indicators of response to treadmill exercise in untrained dogs, is essential in order to evidence the individual levels of exercise tolerance, to investigate exercise-related problems and to design specific and individual treadmill protocols.
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The objective of this study was to compare the method of thermography by using three different resolution thermal cameras and basic software for thermographic images, separating the two persons taking the thermographic images (thermographers) from the three persons interpreting the thermographic images (interpreters). This was accomplished by studying the repeatability between thermographers and interpreters. Forty-nine client-owned dogs of 26 breeds were enrolled in the study. The thermal cameras used were of different resolutions-80 × 80, 180 × 180 and 320 × 240 pixels. Two trained thermographers took thermographic images of the hip area in all dogs using all three cameras. A total of six thermographic images per dog were taken. The thermographic images were analysed using appropriate computer software, the FLIR QuickReport 2.1. Three trained interpreters independently evaluated the mean temperatures of hip joint areas of the six thermographic images of each dog. The repeatability between thermographers was >0.975 with the two higher-resolution cameras and 0.927 with the lowest resolution camera. The repeatability between interpreters was >0.97 with each camera. Thus the between-interpreter variation was small. The repeatability between thermographers and interpreters was considered high enough to encourage further studies with thermographic imaging in dogs.
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Thermography is a practical aid in the clinical evaluation of the equine patient. It is particularly germane to the evaluation of lameness. This modality specifically increases the accuracy of diagnosis. Thermography is the pictorial representation of skin temperature. The technique involves the detection of infrared radiation, which can be directly correlated to blood flow. To be accurate, thermography must be performed in a controlled area free of drafts. The area should be protected from sunlight to avoid erroneous heating of the skin, and the horse's hair length should be uniform. Thermography detects heat before it is perceptible during routine physical examination and thus is useful for the early detection of laminitis, stress fractures, and tendinitis. It offers a noninvasive means of evaluating the blood supply to an injured region and represents one of the only reliable noninvasive means to evaluate blood flow to the foot of the horse. Thermography is also useful for the early identification of stress injuries to the contralateral limb of convalescing orthopedic patients. Thermography is an excellent adjunct to clinical examination as well as being complementary to other imaging techniques such as radiology, ultrasonography, and scintigraphy.
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Equine thermography has increased in popularity recently because of improvements in thermal cameras and advances in image-processing software. The basic principle of thermography involves the transformation of surface heat from an object into a pictorial representation. The colour gradients generated reflect differences in the emitted heat. Variations from normal can be used to detect lameness or regions of inflammation in horses. Units can be so sensitive that flexor tendon injuries can be detected before the horse develops clinical lameness. Thermography has been used to evaluate several different clinical syndromes not only in the diagnosis of inflammation but also to monitor the progression of healing. Thermography has important applications in research for the detection of illegal performance-enhancing procedures at athletic events.
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Reasons for performing study: Thermographic imaging is an increasingly used diagnostic tool. When performing thermography, guidelines suggest that horses should be left for 10-20 mins to 'acclimatise' to the thermographic imaging environment, with no experimental data to substantiate this recommendation. In addition, little objective work has been published on the repeatability and reliability of the data obtained. Thermography has been widely used to identify areas of abnormal body surface temperature in horses with back pathology; however, no normal data is available on the thermographic 'map' of the thoracolumbar region with which to compare horses with suspected pathology. Objectives: To i) investigate whether equilibration of the thermographic subject was required and, if so, how long it should take, ii) investigate what factors affect time to equilibration, iii) investigate the repeatability and reliability of the technique and iv) generate a topographic thermographic 'map' of the thoracolumbar region. Methods: A total of 52 horses were used. The following investigations were undertaken: thermal imaging validation, i.e. detection of movement around the baseline of an object of constant temperature; factors affecting equilibration; pattern reproducibility during equilibration and over time (n = 25); and imaging of the thoracolumbar region (n = 27). Results: A 1 degrees C change was detected in an object of stable temperature using this detection system, i.e the 'noise' in the system. The average time taken to equilibrate, ie. reach a plateau temperature, was 39 mins (40.2 in the gluteal region, 36.2 in lateral thoracic region and 40.4 in metacarpophalangeal region). Only 19% of horses reached plateau within 10-20 mins. Of the factors analysed hair length and difference between the external environment and the internal environment where the measurements were being taken both significantly affected time to plateau (P<0.05). However, during equilibration, the thermographic patterns obtained did not change, nor when assessed over a 7 day period. A 'normal' map of the surface temperature of the thoracolumbar region has been produced, demonstrating that the midline is the hottest, with a fall off of 3 degrees C either side of the midline. Conclusions: This study demonstrates that horses may not need time to equilibrate prior to taking thermographic images and that thermographic patterns are reproducible over periods up to 7 days. A topographical thermographic 'map' of the thoracolumbar region has been obtained. Potential relevance: Clinicians can obtain relevant thermographic images without the need for prior equilibration and can compare cases with thoracolumbar pathology to a normal topographic thermographic map.
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ExtractAdult dogs can survive in an environment in which there are wide variations of temperature because of their ability to regulate their internal temperature.(1)1. Armistead , W.W. and Catcou , E.J. 1979. Canine Medicine, 211–215. Santa Barbara: American Vet. Publications. Inc.. View all references The internal temperature, however, must be maintained within the range of 5°C above normal to 15°C below the normal temperature of blood to avoid cellular injury or death. Thermal homeostasis occurs when there is a balance between “heat load” and heat dissipation. Heat load is defined as the summation of environmental and metabolic heat.(2)2. Krum , S.H. and Osborne , C.A. 1977. Heat Stroke in the Dog: A Polysystemic Disorder. JAVMA, 170(5): 531–535. View all references Heat stroke occurs when heat load markedly exceeds the ability of the body compensatory mechanisms to promote heat loss. In man heat stroke is also due to ineffective thermoregulation. It is caused by the cessation of sweating, which is the main thermoregulatory mechanism. Heat stroke is characterised by hyperthermia (above 105°F), often complicated by alterations in many systems and organs such as acid-base balance, kidney, liver, cerebral oedema, and the blood clotting mechanism.
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To assess the reliability and accuracy of a predictive rectal thermometer, an infrared auricular thermometer designed for veterinary use, and a subcutaneous temperature-sensing microchip for measurement of core body temperature over various temperature conditions in dogs. Prospective study. 8 purpose-bred dogs. A minimum of 7 days prior to study commencement, a subcutaneous temperature-sensing microchip was implanted in 1 of 3 locations (interscapular, lateral aspect of shoulder, or sacral region) in each dog. For comparison with temperatures measured via rectal thermometer, infrared auricular thermometer, and microchip, core body temperature was measured via a thermistor-tipped pulmonary artery (TTPA) catheter. Hypothermia was induced during anesthesia at the time of TTPA catheter placement; on 3 occasions after placement of the catheter, hyperthermia was induced via administration of a low dose of endotoxin. Near-simultaneous duplicate temperature measurements were recorded from the TTPA catheter, the rectal thermometer, auricular thermometer, and subcutaneous microchips during hypothermia, euthermia, and hyperthermia. Reliability (variability) of temperature measurement for each device and agreement between each device measurement and core body temperature were assessed. Variability between duplicate near-simultaneous temperature measurements was greatest for the auricular thermometer and least for the TTPA catheter. Measurements obtained by use of the rectal thermometer were in closest agreement with core body temperature; for all other devices, temperature readings typically underestimated core body temperature. Among the 3 methods of temperature measurement, rectal thermometry provided the most accurate estimation of core body temperature in dogs.
Article
To describe a thermographic imaging protocol, identify normal thermographic patterns (ie, color map reflecting the skin temperature distribution) for various regions of interest (ROIs) of dog limbs, and evaluate effects of clipping the coat on thermographic patterns and limb temperature in healthy dogs. 10 healthy dogs. Each dog was thermographically evaluated in the same room (ambient temperature, 21 degrees C) via ROIs that included cranial and caudal views of the body, full lateral body views, full views of the limbs, and views of various limb regions. After initial imaging, the coat was clipped on the forelimbs and hind limbs only. Each dog was then evaluated 15 and 60 minutes and 24 hours after clipping by use of the same protocol. For each ROI within a category (intact coat and each time point after clipping), mean temperatures were similar among the 10 dogs. Pairwise comparisons for 15 and 60 minutes and 24 hours established patterns of temperature stabilization among the 3 time points. Temperatures did not differ significantly between the left and right limbs. There was a mean success rate of 75% for use of image pattern analysis for recognition of similar thermographic patterns in the forelimbs and hind limbs. Thermography can be a viable, noninvasive imaging modality that provides consistent images with reproducible thermal patterns in ROIs examined in healthy dogs. Although the coat had a predictable influence to decrease the mean temperature, thermal patterns remained fairly consistent after the coat was clipped.
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