Equine Veterinary Journal最新文献

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: 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 (PM_2.5).

Results: BB monitor PM_2.5 and PM₁₀ measurements were linearly correlated with TEOM data (coefficient of determination r² > 0.85 and r² > 0.90 respectively), but underestimated PM_2.5 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 PM_2.5 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.