Equine Veterinary Journal

Background In Great Britain, owners are keeping their horses into increasingly older age, reflecting societal changes in human–animal relationships. The uptake of routine veterinary services is reported to reduce as horses age. Horse owners seek information regarding their animal's health from alternative sources before and/or following veterinary involvement. Information regarding the experiences and behaviours of veterinarians toward older horse health care provision is limited. Objective This study sought to explore how veterinary care for the ageing horse is conceptualised and approached by veterinarians treating horses in Great Britain. Study design Exploratory qualitative. Methods A subset of qualitative data, collected as part of a larger study investigating how owners and veterinarians make decisions regarding the care of the older horses, was analysed using a constructivist grounded theory approach. Data included semi‐structured in‐depth interviews with nine veterinarians and veterinary clinical records pertaining to the horses of 13 participating owners. Results Veterinarians valued regular interactions with owners to optimise a horse's management, however, the timing and nature of veterinary involvement varied. The context of older age shaped decision‐making and ‘age‐appropriate’ interventions were negotiated within the context of each horse and owner. Where participants had concerns about a horse, they sought to achieve an owner's adherence to their advice while navigating the veterinarian–owner relationship. Interpersonal dimensions of veterinarian–owner interactions appeared to shape, and could challenge, veterinarians' delivery of health care services and their own sense of being a professional who cares for animals, and about people. Main limitations A sample of veterinarians were recruited for this study based on horse owners' involvement. Conclusions The provision of veterinary care for the older horse rests upon networks of relationships. Collaboration between the profession and owners in both the design and delivery of, veterinary health care services may better enable different types of knowledge and values to be brought together more effectively.

Background Little information describing the biologic behaviour and therapies for corneal lymphoma exist. Objectives To characterise histologically confirmed equine corneal lymphoma considering breed, age or sex predisposition, histologic and immunologic features, therapies and outcomes. Study design Retrospective case series. Methods A multicentre retrospective medical record review was used to identify horses that presented with corneal disease confirmed morphologically as corneal lymphoma from 2012 to 2022. Results Mean age at diagnosis was 10.5 years. Males represented 18/26 cases. Warmblood (14) and Thoroughbred (6) breeds were most commonly represented. 25/26 had unilateral ocular involvement. No cases had evidence of multicentric lymphoma. Most eyes (77.7%) had a history of suspected immune‐mediated keratitis (IMMK) or eosinophilic keratitis. Morphological diagnosis confirming lymphoma was available for all cases. B‐cell lymphoma was diagnosed in 19/24 eyes for which immunohistochemistry was performed, with intermediate to large B‐cell lymphoma being most common. Fifteen of 27 eyes received at least one form of adjunctive therapy following keratectomy. Four eyes, which did not receive adjunctive therapy following keratectomy, experienced recurrence. No horses treated with adjunctive therapy following keratectomy experienced recurrence. Malignant transformation of IMMK to lymphoma was morphologically documented in one eye and suspected in three others based on recurrence of clinical signs. All globes were retained and visualised at the last follow‐up. Main limitations Incomplete medical records, owner subjectivity concerning onset of disease and cases being lost to follow‐up. Conclusions Malignant transformation of IMMK to corneal lymphoma likely occurs in horses. Lymphoma should be a differential for nonulcerative keratitis in horses. Keratectomy and histopathology may be considered in progressive or refractory cases of IMMK to rule out neoplastic disease. Recurrence of corneal lymphoma is unlikely following excision and adjunctive therapy. Cases with large corneal surface area or deep stromal involvement may have a likelihood for recurrence.

The suspensory ligament (SL) is a key component of the elaborate and highly adapted suspensory apparatus in the horse. In addition to contributing to stabilisation of the metacarpophalangeal joint, the SL has a spring like function to reduce the energetic cost of locomotion. Although the SL is highly prone to injury in horses of all ages and competing in a wide range of disciplines, knowledge regarding fundamental structure–function relationships in the SL is lacking, particularly compared with other injury‐prone tendinous structures such as the superficial digital flexor tendon. In this review, we discuss current knowledge of SL composition, structure and mechanical properties and describe the epidemiology, aetiology and pathophysiology of injuries. We evaluate different diagnostic approaches and treatment modalities and identify key areas for future research.

Background MicroRNA (miRNA) has previously been used as a biomarker for cardiac disease in humans and dogs, however, studies in horses are not yet available. Objectives To determine if adult horses with moderate or severe mitral valve regurgitation have a different serum miRNA expression profile compared to healthy controls. Study design Retrospective cross‐sectional. Methods Serum samples from 77 adult horses with moderate or severe mitral valve regurgitation and 77 healthy control horses were analysed using a commercial cardiac disease‐specific miRNA panel previously used in dogs. Results The commercial canine cardiac miRNA panel had low discriminatory power as a biomarker for mitral valve regurgitation in adult horses. Sensitivity was 0.58 (95% Cl: 0.47–0.69) and specificity 0.57 (95% Cl: 0.46–0.68). Main limitations Clinical data were extracted retrospectively and currently there is no well‐established criteria for grading mitral regurgitation in horses; there were few severe mitral regurgitation cases and the pathogenesis of mitral regurgitation was not considered. Controls were not matched by age, breed or sex. An assay developed for use in dogs was used. Conclusion Despite strong miRNA conservation across species, the commercially available canine cardiac miRNA panel failed as biomarker for mitral valve regurgitation in adult horses. Further research is needed to determine if an equine specific panel can be developed that performs better as biomarker for cardiac disease in horses.

Background Traditional radiographic measurements of distal phalanx (Pd) displacement based on the outer hoof wall are not useful for diagnosis of acute laminitis. Objectives We hypothesised that the distance between the inner hoof wall and Pd (‘lamellar lucent zone’; LLZ) measured on lateromedial digital radiographs would be increased in horses with acute and subacute laminitis compared with healthy horses. Study design Retrospective cohort study and in vivo experimental study. Methods Forelimb radiographs from 32 healthy and 18 laminitic mixed‐breed horses were analysed retrospectively. Laminitis was defined by at least two clinical signs (acute multi‐limb lameness, increased digital pulse amplitude and/or persistently warm hooves) for ≤3 days (acute), or >3 and ≤14 days (subacute) duration, without overt palmar rotation (≥3°), remodelling, or distal displacement of the Pd. Some laminitic limbs initially classified as acute were subsequently radiographed later in hospitalisation and also included as subacute. Twelve measurements including LLZ at proximal, middle, and distal locations were performed on 126 forelimb radiographs that met the criteria for acute laminitis (n = 39), subacute laminitis (n = 23) or healthy control (n = 64). A mixed effects linear regression model was used for comparisons and a receiver‐operator characteristic (ROC) curve was created for select measurements. Three horses were serially radiographed to study the impact of magnification and obliquity. Results The mean [95% confidence interval] LLZ (mm) was increased in acute and subacute laminitis compared with control in the proximal (acute = 8.8 [8.4–9.2]; subacute = 9 [8–9.9]; control = 7.3 [7–7.7]), middle (acute = 8.9 [8.5–9.3]; subacute = 9.1 [8.2–10]; control = 6.9 [6.5–7.2]), and distal (acute = 9.1 [8.5–9.7]; subacute = 10.2 [9.1–11.3]; control = 7.5 [7.2–7.8]) dorsal lamellar regions (p < 0.001). At a cut‐off of >7.5 mm for middle LLZ, sensitivity was 87% [73%–94%] and specificity 91% [81%–96%] for diagnosis of acute laminitis. Using the ratio of middle LLZ to distal phalanx cortical length, sensitivity was 95% [81%–99%] and specificity was 95% [87%–99%] (cut‐off >0.11). Magnification and obliquity affected absolute LLZ measurements but did not alter LLZ ratios. Main limitations No histological confirmation of laminitis. Conclusions LLZ measurements are potentially useful for radiographic diagnosis of acute and subacute laminitis.

Background While previous reports come mostly from the southern Americas, several outbreaks of hypersalivation in horses were observed in Middle Europe from 2016 to 2018. Objective To describe feed‐induced hypersalivation in European horses. Study design Analysis of feedstuffs. Methods Veterinarians and horse or stable owners were encouraged to submit feedstuffs from case outbreaks of hypersalivation in which, infectious diseases or other systemic causes of the syndrome were ruled out and intoxication was suspected. Feedstuff analysis was performed, including gross examination, microscopic analysis of fine particles, and for hay and forage mycological culturing and mycotoxin testing. Results Eleven case outbreaks were investigated. Typical clinical findings in the horses were either foamy saliva around the mouth or serous salivation with puddles forming on the ground. Some horses also showed lesions of the gingival mucosa and/or the tongue. Foamy hypersalivation, sometimes combined with lesions of tongue and/or gingiva, was associated with finding of ergot sclerotia and ergot alkaloids in hay or pasture plants (ergocornin and ergocorninin having the highest concentrations). Serous hypersalivation with massive loss of fluid was associated with the fungus Rhizoctonia spp. As indicated by the detection of traces of swainsonine, mycotoxin production on the forage was seen as likely cause. The cessation of clinical signs took days to weeks after diet change, probably depending on the duration, type and amount of toxin intake. Main limitations Small number of case outbreaks, records of clinical findings and horses' management were incomplete and were reported by horse owners. Conclusion Hypersalivation due to mycotoxins in the feed has become an emerging problem for horses in middle Europe.

Background Fragile foal syndrome (FFS) or warmblood FFS Type 1 (WFFS) is a recessive, autosomal, hereditary, genetic defect causing late abortions, stillbirths and non‐viable foals. Whether early pregnancy losses occur is unknown. Objectives To investigate how WFFS affects pregnancies and whether early pregnancy losses occur in WFFS matings and if there is a difference in pregnancy success between matings where both parents were allele carriers and those where only mare or stallion were WFFS carriers. Study design Retrospective cohort study. Methods Breeding records from a Warmblood stud farm were evaluated (2016–2019) and 2682 cycles of 177 mares analysed. Matings were assigned to four study groups, depending on the WFFS carrier status of the mare and stallion: N/WFFS × N/WFFS (n = 46), N/WFFS (mares) × N/N (n = 511), N/N × N/WFFS (stallions) (n = 191) and N/N × N/N (n = 2149). Results There were no differences in pregnancy rates between matings with only one WFFS carrier and those with non‐carriers. When comparing N/WFFS × N/WFFS matings to those with only one or no WFFS‐carrier, there were no increased pregnancy losses in the embryonic phase (day <42). By contrast, the N/WFFS × N/WFFS group had significantly more abortions (53.8%) than the other three study groups (7.9–9.2%; adjusted p < 0.0001). The higher losses were evenly distributed between the early (D42–150: 22.7% losses, n = 5) and late (D150–300: 29.4% losses, n = 5) foetal phase. The live foal rate per pregnancy for N/WFFS × N/WFFS matings was lowest (34.5%) and differed significantly (other groups 81%–84%; adjusted p < 0.0001); the peri‐ and postnatal mortality was higher (25%) compared with the other study groups (2.6%–3%). Main limitations Low sample size in N/WWFS × N/WFFS matings, unbalanced study design, outcomes are descriptive, all mares from one stud farm. Conclusions The mating of two WFFS carriers may lead to increased risks of pregnancy and foal loss.

Background Warmblood horses are a popular breed around the world for equestrian sports. Previous studies have investigated ocular findings in other breeds of horses; however, no studies exist for the Warmblood breed. Objectives To determine the prevalence of ocular abnormalities in a convenience sample of Warmblood horses in South Africa and to determine if the prevalence of lens and chorioretinal lesions increase with age. Study design Descriptive, observational study. Methods Warmblood horses underwent a full ophthalmic examination which included a Schirmer tear test (STT), tonometry, fluorescein dye testing, slit lamp biomicroscopy and indirect ophthalmoscopy. Age was categorised into three groups namely <8 years old, 8–13 years old and 14+ years old for statistical analysis. Prevalence of lens and chorioretinal lesions were compared between age categories. Results One hundred and four horses (208 eyes) were examined. The age range was 5 months to 30 years (mean 11 years, standard deviation [SD] 6 years). Ocular pathology was noted in 125 eyes (60.1%) and 79 horses (76%). The highest number of lesions were noted in the choroid and retina, iris and lens. Chorioretinal lesions were seen in 100 eyes (48.1%) and in 65 horses (62.5%). Iridial lesions were seen in 19 eyes (9.1%) and 12 horses (11.5%). Cataracts were seen in 19 eyes (9.1%) and in 13 horses (12.5%). The presence of total chorioretinal lesions (eye level [p = 0.002]; horse level [p = 0.004]), focal chorioretinal lesions (eye level [p = 0.004]; horse level [p = 0.008]) and cataract (eye [p = 0.03]; horse level [p = 0.02]) were all shown to statistically increase with age. Main limitations A small sample size and limited geographic area. Conclusions There was a high prevalence of ocular pathology in this population of Warmblood horses in South Africa. This reiterates the importance of an ocular examination as a part of routine health checks, as well as during prepurchase examinations.

Background Reliable lameness thresholds for vertical head displacement for trotting on a circular path and on different surfaces have yet to be defined. Withers movement in lame horses could help improve the diagnostic accuracy of sensor technology. Objectives To define head movement lameness threshold ranges and describe the relationship between head and withers movement during trotting under different circumstances in sound and forelimb lame horses. Study design Retrospective analysis of clinical data and comparison with control group. Methods Fifty‐five sound and thirty‐four naturally lame horses were trotted under field conditions on a hard surface on a straight line and on both directions on soft and hard surfaces. Movement asymmetry was analysed by measuring differences in displacement minima for head and withers using an inertial measurement unit sensor‐based gait analysis system. Receiver operating characteristic (ROC) analysis was performed to define threshold ranges. Relationships between head and withers data were identified by calculating the correlation with linear regression analysis. Results Estimated lameness threshold values for vertical head movement asymmetry ranged from 11.5 to 12.5 mm. On both surfaces, a head movement asymmetry threshold range from 24.5 to 26.5 mm could be found for the circle. Lame horses showed significant correlations between head and withers movement on hard ground straight line (R² 0.714, p < 0.001) and inner leg lame horses on the lunge (R² 0.915, p < 0.001). Main limitations Different sources of lameness were not distinguished. Radius and speed during lungeing could not be perfectly controlled. Inclusion in the sound group was based on a subjective examination by one clinician and in the lame group two clinicians subjectively determined inner and outer leg lameness creating an extra amount of uncertainty. Conclusions Lameness thresholds for quantifying head movement asymmetry on the lunge were proposed. A significant correlation was observed between head and withers movement asymmetry under several conditions.

Background A proportion of senior horses (≥15 years of age) are still used for competition. Information about this particular group of horses is currently sparse. Objectives To provide an overview of the demographics, management and health of competing U.S. senior horses (≥15 years of age). Study design Online survey. Methods Descriptive and inferential (Kruskal–Wallis test) analysis of 246 surveys from owners of U.S.‐resident senior horses used for competition. Confidence intervals were calculated for prevalence estimates of clinical signs and medical conditions. Results Competing senior horses were mainly kept at their owners' own facility, with owners making all management decisions (52.2%). In terms of housing, competing senior horses were most frequently kept in a stall but with ≥12 h a day on pasture. Competing seniors were predominantly 15–20 years of age (73.4%), were geldings (69.5%) and were Quarter Horses (33.5%). About one‐half competed/trained for competition at a medium level. Three percent competed at the highest (e.g., international) level. The most common discipline was dressage (32.0%). Stiffness/reduced leg‐joint flexibility was the most common owner‐reported clinical sign (29.2%; 95% CI: 23.5–35.6) and osteoarthritis was the most common owner‐reported veterinary‐diagnosed medical condition (32.6%; 95% CI: 26.8–39.0), followed by gastric ulcers (8.0%; 95% CI: 5.1–12.3) and lameness (7.6%; 95% CI: 4.8–11.8). Nearly one‐half (43.3%) indicated that their competing senior horse had no veterinary‐diagnosed medical condition at the time of the survey. Main limitations Potential recall, response and sampling bias. Conclusions Although few horses over 20 years of age were used in competition, senior horses (≥15 years of age) competed up to the highest level (e.g., internationally) in some disciplines. Competing senior horses were affected by medical conditions commonly reported in the general senior horse population (e.g., osteoarthritis and lameness) and younger competing horses (e.g., gastric ulcers and lameness), potentially increasing the complexity of their management.

Background In anaesthetised horses, bradycardia secondary to high vagal tone can reduce cardiac output and blood pressure. The use of anticholinergics in horses is limited due to concerns about ileus and abdominal discomfort. This retrospective study sought to determine the prevalence of post‐operative abdominal discomfort in healthy horses that received atropine under isoflurane anaesthesia. Study design A retrospective evaluation of 222 general anaesthesia events between January 2019 and December 2019 was undertaken. Methods One hundred and eleven horses that received atropine were identified, and 111 case match controls that did not receive atropine were also selected. Information gathered from the medical records included signalment, anaesthetic drugs, surgical procedures, duration of anaesthesia and surgery, dobutamine and atropine administration, and the occurrence of abdominal discomfort for 24 h after anaesthesia. After initial data analysis, a second cohort of records was assessed separately. The horses in this group were castrated under general anaesthesia (with or without atropine; n = 68). Logistic regression models and Fisher's exact tests were used to look for factors contributing to abdominal discomfort post‐anaesthesia. The significance level was set to 5% (p < 0.05). Results Atropine administration was not associated with the development of post‐anaesthetic abdominal discomfort (OR = 2.121, 95% CI [0.767, 5.869]; p = 0.2). Overall, 18/222 (8.1%) incidences of abdominal discomfort were identified. All incidents occurred in colts undergoing castration. In a separate analysis of only horses anaesthetised for castration, atropine was associated with developing abdominal discomfort (OR = 3.143, 95% CI [1.082, 9.132]; p = 0.04). Discussion Atropine was not associated with post‐operative abdominal discomfort except in colts undergoing castration. All episodes of discomfort were mild and resolved with minimal intervention. The potential impact of insufficient analgesia in horses undergoing castration is a confounding factor and requires prospective investigation. Conclusion Overall, atropine at a dose of 0.006 mg/kg IV appears to be a safe method to treat bradycardia in otherwise healthy horses anaesthetised for orthopaedic and upper airway procedures. Further work is required to determine if atropine is safe for colts undergoing castration.

Background Affordable particulate matter (PM) monitors suitable for use on horses will facilitate the evaluation of PM mitigation methods and improve the management of equine asthma. Objective Calibrate a real‐time wearable PM monitor (Black Beauty [BB]) and compare the PM exposures of horses fed dry or soaked hay. Study design Laboratory calibration; complete cross‐over feed trial. Methods Side‐by‐side sampling with BB monitors and tapered element oscillating microbalances (TEOMs) was performed under varying concentrations of PM from alfalfa hay. Linear regression was used to derive a calibration formula for each unit based on TEOM PM measurements. Precision was evaluated by calculating the coefficient of variation and pairwise correlation coefficients between three BB monitors. PM exposure was measured at the breathing zone of 10 horses for 8 h after they were fed dry or soaked hay. Repeated measures generalised linear models were constructed to determine the effect of hay treatment and measurement duration (initial 20‐min vs. 8‐h) upon exposure to PM with diameters smaller than or equal to 10 μm (PM10) and 2.5 μm (PM2.5). Results BB monitor PM2.5 and PM10 measurements were linearly correlated with TEOM data (coefficient of determination r² > 0.85 and r² > 0.90 respectively), but underestimated PM2.5 mass concentrations by a factor of 4 and PM10 concentrations by a factor of 44. Measures from the three BB monitors had a coefficient of variation <15% and pairwise r > 0.98. Feeding soaked hay significantly reduced average PM2.5 exposures (20‐min: dry: 160 μg/m³, soaked: 53 μg/m³, p < 0.0001; 8‐h: dry: 76 μg/m³, soaked: 31 μg/m³, p = 0.0008) and PM10 exposures (20‐min: dry: 2829 μg/m³, soaked: 970 μg/m³, p < 0.0001; 8‐h: dry: 1581 μg/m³, soaked: 488 μg/m³, p = 0.008). Main limitations No health outcome measures were collected. Conclusions With appropriate corrections, the BB monitor can be used to estimate horse PM exposure. While 20‐min measurements yielded higher estimates of exposure than 8‐h measurements, both intervals demonstrate that soaking hay reduces PM exposures by more than 50%.

Background Equine post‐operative morbidity represents a significant concern for both veterinary surgeons and horse owners. Objectives To estimate the prevalence of post‐operative complications in horses after elective/non‐abdominal surgery or colic surgery. Study design Systematic review. Methods A database search identified eligible studies which reported the prevalence of equine post‐operative complications published as a full paper in English in a peer‐reviewed journal between 2000 and 2023. Studies were evaluated using the JBI Critical Appraisal Checklist for Prevalence Studies and GRADE (Grading of Recommendations, Assessment, Development and Evaluations) framework. Data for the most commonly reported complications were analysed using Chi‐squared analysis of weighted means to answer 13 PICO (Population, Intervention, Comparator and Outcomes) questions. Results Sixty‐seven studies met inclusion criteria. Data for eight post‐operative morbidities (colic, surgical site complications, myopathy/neuropathy, laminitis, diarrhoea/colitis, fever/pyrexia, jugular thrombophlebitis/thrombosis, respiratory complications) were sufficient to allow statistical analyses. The weighted mean of the overall proportion of post‐operative complications after elective/non‐abdominal surgery is 17.48% (95% confidence interval [95% CI]: 13.20–22.92), significantly increasing to 55.62% (95% CI: 45.79–65.03) after colic surgery (odds ratio [OR] 6.63; 95% CI: 5.83–7.56; p < 0.001). The most commonly reported morbidity was post‐operative colic, with a weighted mean prevalence of 7.45% (95% CI: 4.83–11.76) after elective/non‐abdominal surgery, significantly rising to 26.46% (95% CI: 19.11–35.97) after colic surgery (OR 4.11; 95% CI: 3.60–4.71; p < 0.001). The weighted mean prevalence of surgical site complications, laminitis, diarrhoea/colitis, fever/pyrexia, jugular thrombophlebitis/thrombosis and respiratory complications were significantly higher after colic surgery compared with elective/non‐abdominal surgery. Myopathy/neuropathy was the only morbidity where prevalence was not different between groups (OR 1.86; 95% CI: 0.86–4.16; p = 0.16). Main limitations The majority of studies were retrospective. Morbidity definitions, data collection periods, follow‐up time and methods varied between studies. Conclusions Based on current evidence, the prevalence of post‐operative colic, surgical site complications, laminitis, diarrhoea/colitis, fever/pyrexia, jugular thrombophlebitis/thrombosis and respiratory complications is significantly higher after colic surgery compared with elective/non‐abdominal surgery under general anaesthesia.

Sustained atrial tachycardia at an atrial rate of 191/min on the surface ECG was detected in a 6‐year‐old Warmblood mare. The vectorcardiogram obtained from a 12‐lead ECG suggested a caudo‐dorsal right atrial origin of the arrhythmia. Impedance‐based three‐dimensional electro‐anatomical mapping, using the EnSite™ Precision Cardiac Mapping System revealed a clockwise macro‐reentry around a line of conduction block in the caudomedial right atrium. Ten radiofrequency applications were applied to isolate the caudal vena cava myocardial sleeves at a power of 35 W and mean contact force of 14 ± 3 g until a lesion size index of 6 was reached. Sinus rhythm was restored at the first energy application. Successful isolation was confirmed by demonstrating entrance and exit block. Holter monitoring 5 days post‐ablation revealed no abnormalities. To date, 9 months after treatment, no recurrence has been observed. The use of lesion size index‐guided ablation and isolation of the arrhythmogenic substrate in the caudal vena cava may minimise the risk of recurrence.

Background Endometritis is the leading cause of subfertility in horses, and it is a clinical problem where historically antibiotics have not always been used with prudent justification. Because of this, alternative therapies to treat endometritis are necessary for the rational use of antibiotics. Objectives To assess the in vitro antimicrobial activity of non‐traditional therapies commonly used in clinical practice against microorganisms causing infectious endometritis in mares. Study design In vitro experiments. Methods A microdilution technique was performed to determine the minimum inhibitory concentrations (MIC) of 50%, 90% and 100% of microorganisms and the percentage of inhibition (PI) of each therapy against each microorganism (Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus and Candida sp.). The MIC 50% and 90% were determined using non‐linear regression, while MIC 100% was assessed using the resazurin dye technique. The serial PI was evaluated for each therapy using a spectrophotometer. Results All the therapies demonstrated a PI higher than positive controls for all microorganisms (p < 0.05); however, the only therapies that presented MIC 100 values were hydrogen peroxide and platelet‐rich and ‐poor plasma. Main limitations In vivo, safety and treatment efficacy were not tested. Conclusion Hydrogen peroxide and platelet‐rich and ‐poor plasma might be alternatives to traditional therapies for endometritis to support a reduction in antibiotic use.

Background Data on equine thoracic pathology hardly exist in breeds other than Thoroughbreds. Objectives To describe pathological changes of the osseous thoracic vertebral column in Warmblood horses, Shetland ponies and Konik horses, and to compare prevalence and severity. Study design Descriptive post‐mortem study. Methods Computed tomography was used to examine the thoracic vertebral column of 34 Warmblood horses, 28 Shetland ponies, and 18 Konik horses. Osteoarthritis (OA), periarticular osteolysis, osseous cyst‐like lesions and fragments of articular processes (APJs), costovertebral and costotransverse joints, soft tissue mineralisation surrounding these joints, intervertebral disc (IVD) mineralisation, impingement of spinous processes (SPs) and spondylosis were scored. Results APJ aplasia (98%; 58/59) occurred in 14 Shetland ponies. OA predominated in Warmblood horses across all joints (45% vs. 29 and 32%, p < 0.001). OA and periarticular osteolysis were found in particular in the costotransverse joints (p < 0.001) across all breeds. Warmblood and Konik horses had more and severe soft tissue mineralisation than Shetland ponies (2.3%, score 1.5 and 3.2%, score 1.3, respectively, vs. 0.3%, score 0.9, p < 0.01). Mid location was most often affected with highest severity score (4.2%, 1.5, p < 0.001). Konik horses displayed the highest IVD mineralisation (20%, p < 0.001), which notably increased with age (p < 0.001) compared with Warmblood horses (4.5%) and Shetland ponies (1.1%). SPs impingement was absent in Shetland ponies, and most prevalent in Warmblood horses (11.2%, p < 0.001) compared with Konik horses (2.2%). Osseous cyst‐like lesions, fragments and spondylosis were minimal in all breeds and nearly absent in Shetland ponies. Main limitations Clinical histories and macroscopic and histologic examinations were unavailable. Conclusions Distinct breed differences exist in prevalence and severity of thoracic vertebral column osseous pathologies. Costotransverse joint pathology is more common than APJ pathology in all breeds. Warmblood horses are prone to OA, spondylosis and SPs impingement; Konik horses exhibit significant IVD mineralisation, and Shetland ponies demonstrate a high prevalence of APJ aplasia. Periarticular osteolysis, osseous cyst‐like lesions, fragments and soft tissue mineralisation are notably low in Shetland ponies.

Background Computed tomography (CT) of the axial skeleton is increasing across many equine hospitals. CT of the pelvis and caudal spine in a large group of clinical cases has not been reported previously. Objective To describe the pathological lesions identified in the caudal spine/pelvis in horses and ponies undergoing CT spine of this region. Study design A retrospective case series. Methods Horses with CT imaging of the caudal spine/pelvis were included. Horses aged under 6 months and those with CT examinations performed post‐mortem were excluded. Results Fifty‐six horses met the inclusion criteria. Ages ranged from 8 months to 20 years and bodyweights from 85 to 680 kg (mean 488 kg). Horses presented predominantly for lameness (30/56) and poor performance (18/56). Osseous pathology was identified in 41/56 horses; including osteoarthritis of the sacroiliac joint(s) (n: 28), pathology of the intervertebral disc joint(s) (n: 12), pelvic fractures (n: 9), osteoarthritis of the coxofemoral joint(s) (n: 8), ventral spondylosis (n: 6), acetabular rim fracture (n: 2), dislocation of coxofemoral joint(s) (n: 2), and dorsal dermal sinus of the sacrum (n: 1). Main limitations The relationship between CT imaging findings and clinical signs in horses remains unclear. Further work is required to describe the relationship between congenital, developmental, and acquired changes in the caudal spine and pelvis, and clinical signs. Conclusions CT of the caudal spine and pelvis can be utilised in horses and ponies for diagnosing a range of clinical disorders that may be causing ‘lumbosacroiliac pain’, poor performance, hindlimb lameness, and stiffness. The pathologies we observed were diverse and many patients had multiple lesions.

Background Foal immunity relies heavily on the absorption of colostrum immunoglobulins; thus, colostrum evaluation is used to predict the transfer of passive immunity (TPI), and its conductivity is associated with TPI in cattle. Leading up to and at parturition, a reduction in colostrum pH and conductivity is thought to be necessary for TPI; however, this remains to be determined. Objectives To assess conductivity, pH, and Brix refractometer index of colostrum to predict the TPI in foals. Study Design Field study. Methods The colostrum of 241 mares was assessed for conductivity, pH, and Brix index using handheld devices immediately after parturition. Twenty‐hour postpartum foals had complete blood cell count and plasma IgG concentrations assessed. Foals were split in complete versus incomplete TPI (i.e., IgG ≥8 g/L vs. <8 g/L). Mare (breed, duration of pregnancy, parity, and age), foal (sex), and colostrum (conductivity, pH, and Brix index) data were computed to assess factors affecting TPI. Multivariate regression and receiver operating characteristic (ROC) curves were employed for analysis. Results Complete TPI was achieved in 89.4% of foals. The ROC TPI values were conductivity ≤5 mS/cm (AUC = 0.68), Brix ≥23.4% (AUC = 0.70), and pH ≤6.4 units (AUC = 0.73). The odds ratio for TPI in 24 h post‐partum was 6.1 (2.1–17.1, 95% CI) for conductivity, 3.2 (1.2–9.3, 95% CI) for pH, and 4.5 (1.5–12.7, 95% CI) for Brix index. Sensitivity and specificity of 93% (88–96 95% CI), 56% (44–7, 95% CI), 92% (87–96, 95% CI), 28% (14–47, 95% CI), 94% (88–97, 95% CI) and 18% (14–47, 95% CI) for conductivity, Brix and pH, respectively. Main limitations Low incidence of incomplete TPI. Conclusions Conductivity, pH and Brix are strong predictors of foals that succeed in the transfer of passive immunity; however, all three presented low to moderate specificity. The established cutoff values obtained herein can be used on‐field by other foaling programs. All three handheld devices used in the study are inexpensive and ready to use on‐farm.

Background Cross‐sectional imaging improves the diagnostic accuracy of complex anatomical regions. Computed tomography (CT) of the pelvis and caudal spine in a large group of live horses and ponies has not been previously reported. Objective To describe the procedure for acquiring CT images of horses' caudal spine/pelvis under general anaesthesia (GA) and to detail the image quality, artefacts and anatomical variations in this region. Study design Retrospective case series. Methods Horses with CT of the caudal spine/pelvis were included. Horses under 6 months and CT examination performed post‐mortem were excluded. Protocols, image quality, region of interest, anatomical features and morbidities were analysed. Results Fifty‐six horses (8 months to 20 years, 85–680 kg) met the inclusion criteria. GA ranged from 10 to 60 min (mean: 30, median: 32). There were no adverse events recorded in any of the horses associated with the procedure. Images of all horses were considered of diagnostic quality. Anatomical variations were common and included the location of diverging (widest) interspinous space, the presence of spina bifida in the lumbar and sacral spine, the shape of the last lumbar vertebra and the location of intertransverse joints in terms of where they were present and the degree of fusion/modelling. Main limitations Not all horses underwent CT examination of the same regions, the upper size limit of horses is unknown and will vary depending on bore size and table infrastructure. Image noise, particularly in large horses and beam hardening artefacts from hardware and pelvis degraded image quality. Images were of insufficient quality in large horses for soft tissue interpretation. Conclusion CT of the caudal spine and pelvis in live horses with wide‐bore CT machines and modified patient infrastructure was safe and produced diagnostic images.

Background Equine corneal disease is common and painful. Current pain mitigation strategies are often suboptimal, especially early in the disease. Objectives To evaluate the effects of local anaesthetic delivery via indwelling retrobulbar catheter on corneal sensitivity, pupil size, pupillary light responses (PLRs), and ocular motility in normal horses. Study design Randomised, controlled crossover experiment. Methods One eye was randomly selected from seven horses. A 20‐gauge catheter was placed in the retrobulbar space and injected with 10 mL of 0.5% bupivacaine or 0.9% saline. Cochet–Bonnet esthesiometry (CBE), pupil photogrammetry, PLRs, and oculocephalic reflexes were evaluated before injection (t = 0) and t = 0.25, 1, 3, 6, 9 and 12 h after injection. Following a 7–14 day washout period, this procedure was repeated using the alternative injection solution. Corneal touch thresholds (CTTs) derived from CBE and pupillary areas (PA; as measured from photographs) were compared across time for each group. PLRs and oculocephalic reflexes were compared between groups at each evaluation time point. Results Saline did not affect CBE, PA, PLRs or oculocephalic reflexes at any time point. Bupivacaine reduced CTT compared with saline for 6 h, with maximum reduction at t = 1 h (bupivacaine: 0.08 ± 0.20 cm; saline: 4.21 ± 0.39 cm; p < 0.001). Bupivacaine increased PA compared with saline for 3 h, with maximum increase at t = 3 h (bupivacaine: 349.75 ± 84.80 mm²; saline: 194.65 ± 27.03 mm²; p = 0.04). Bupivacaine injection reduced PLRs for 9 h and oculocephalic reflexes for 3 h; saline had no effect. Mild adverse effects included chemosis, blepharoedema, and transiently reduced palpebral reflex. Main limitations Reduction in CTT may not directly translate to pain control in clinical horses with corneal disease. Adverse effects of repeated injections were not evaluated. Conclusions Injection of bupivacaine via an indwelling retrobulbar catheter in horses reduces corneal sensitivity and may be useful in reducing pain in horses with corneal disease.

Data available about clinical-diagnostic and therapeutic management of neonatal equine piroplasmosis (EP) are limited. Vertical transmission of EP is underestimated, mainly in endemic areas. Objectives: To describe the clinical-diagnostic and therapeutic workup of foals with hyperacute EP infection in an endemic area in northern Italy.

Background Poor noseband adjustment could create high pressures that may risk pain or tissue damage. Objectives To quantify sub‐noseband pressures dorsally over the nasal bone and ventrally over the mandibular rami for a Cavesson, Swedish (crank), Drop and Flash noseband at five tightness levels (2.0 to 0.0 finger equivalents). Study design In vivo experiments. Methods Eight high‐level dressage horses were ridden at the trot in a straight line by their usual riders. Two small pressure mats, attached to the noseband over the nasal bone and the mandibular rami, collected force (N) and pressure (kPa) data from four noseband types (Cavesson/Swedish/Flash/Drop) each adjusted to five tightness levels (2.0/1.5/1.0/0.5/0.0 finger equivalents) based on the use of a taper gauge. Noseband tightness and types were compared using Friedman's analyses with post hoc Wilcoxon tests (p ≤ 0.01). Results Pressures (median and [25th and 75th percentiles]) and forces increased with tightness for all noseband types with higher mean pressures consistently recorded on the mandibles (Cavesson: 9.1 [5.0, 12.5] kPa, Swedish: 10.5 [6.3, 14.9] kPa, Flash: 8.0 [3.6, 15.2] kPa) than the nasal bones (Cavesson: 2.8 [1.1, 4.7] kPa, Swedish: 4.3 [3.1, 7.4] kPa, Flash: 4.9 [3.0, 7.3] kPa, p ≤ 0.002). None of the measured nasal pressures or forces differed significantly between tightness levels of 2.0 (1.6 [0.6, 3.6] kPa) and 1.5 fingers (2.9 [1.3, 4.1] kPa), but these values significantly increased from 1.0 (3.1 [1.5, 4.9] kPa), 0.5 (4.2 [2.3, 6.2] kPa), and 0.0 finger tightness (6.4 [3.8, 10.3] kPa) for most variables (p ≤ 0.004). No differences were found in mean/maximal nasal and mandibular pressures when fitted with a Cavesson or Swedish noseband. Main limitations Behavioural and physiological parameters were not measured. Conclusions Nasal and mandibular pressures increased with noseband tightness, with 1.0 finger laxity or less associated with significantly and incrementally higher pressures than 1.5 or 2.0 finger tightness.