Equine Veterinary Journal publishes evidence to improve clinical practice or expand scientific knowledge underpinning equine veterinary medicine. This unrivalled international scientific journal is published 6 times per year, containing peer-reviewed articles with original and potentially important findings. Contributions are received from sources worldwide.
SummaryFive hundred four‐year‐old Standardbred Trotters in training were examined in a study on the correlation between conformation, soundness and racing performance. In 39 horses marked hindquarter asymmetries were observed when they were standing squarely on all four feet. The asymmetries were seen as obvious height differences between the left and right tubera sacrale. In 30 cases the left tuber sacrale was lower and in nine cases the right tuber sacrale was lower. The horses showing hindquarter asymmetry were of significantly larger body size than the 461 horses not showing the asymmetry. There was no sex difference in the incidence of hindquarter asymmetry. The asymmetric horses had significantly lower total earnings, a lower number of races per horse and less good racing records (min/km) than the remaining 461 horses. The trainers reported that the asymmetric horses often had difficulties in performing at speed. In most horses, the asymmetry had not been observed until the examination. Past clinical records of 11 of the 30 asymmetric horses were available. In only one of the 11 horses had the asymmetry been considered of clinical importance. It was concluded that the described hindquarter asymmetries are important signs indicating that there is an enhanced risk that the affected horses will not become successful Trotters.
SummaryReasons for performing study: Research has highlighted a high frequency of skeletal asymmetries in horses. In addition, research into hoof asymmetries has shown that within a bilateral pair, the hoof with the smaller angle is often subjected to greater loading. There has been limited attention paid to understanding compensatory mechanisms for skeletal asymmetries in the horse; the dynamic structure of the hoof could potentially be acting in a compensatory capacity.Objectives: To investigate the relationship between morphometry of forelimb segments and hoof spread and their incidence of asymmetry.Methods: Ten bilateral measurements of the hoof and forelimb were taken from 34 leisure horses. The relationship between hoof spread and forelimb segment measurements were analysed using a generalised linear model (GLM).Results: In relation to left hoof spread, the GLM identified significant negative relationships with left side measurements (third metacarpal length, elbow height), and significant positive relationships with right side measurements (fetlock height, third metacarpal length, elbow height). In relation to right hoof spread, the GLM identified significant negative relationship with left elbow height, and significant positive relationships with right side measurements (fetlock height, point of shoulder). The difference between the number of horses larger to the left or to the right was found to be significant for point of shoulder height (X2= 4.8, P<0.05), and highly significant for heel height (X2= 9.53, P<0.01) and the third metacarpal length (X2= 7.26, P<0.01).Conclusions and clinical relevance: The study demonstrated considerable asymmetry in left‐right morphometry of the equine limb. The fact that measurements of hoof spread were significantly associated with limb segment measurements could possibly indicate that an interaction exists. Any asymmetry in hoof spread measurements may suggest unequal loading of the limbs, which in turn may contribute to injuries and reduced performance.
Elizabeth J. Davidson, Benson B. Martin, RC Boston, Eric J. Parente
SummaryReasons for performing study:Although well documented in racehorses, there is paucity in the literature regarding the prevalence of dynamic upper airway abnormalities in nonracing performance horses.Objective:To describe upper airway function of nonracing performance horses with abnormal respiratory noise and/or poor performance via exercising upper airway videoendoscopy.Methods:Medical records of nonracing performance horses admitted for exercising evaluation with a chief complaint of abnormal respiratory noise and/or poor performance were reviewed. All horses had video recordings of resting and exercising upper airway endoscopy. Relationships between horse demographics, resting endoscopic findings, treadmill intensity and implementation of head and neck flexion during exercise with exercising endoscopic findings were examined.Results:Dynamic upper airway obstructions were observed in 72% of examinations. Head and neck flexion was necessary to obtain a diagnosis in 21 horses. Pharyngeal wall collapse was the most prevalent upper airway abnormality, observed in 31% of the examinations. Complex abnormalities were noted in 27% of the examinations. Resting laryngeal dysfunction was significantly associated with dynamic arytenoid collapse and the odds of detecting intermittent dorsal displacement of the soft palate (DDSP) during exercise in horses with resting DDSP was only 7.7%. Exercising endoscopic observations were different from the resting observations in 54% of examinations.Conclusions:Dynamic upper airway obstructions were common in nonracing performance horses with respiratory noise and/or poor performance. Resting endoscopy was only helpful in determining exercising abnormalities with recurrent laryngeal neuropathy.Potential relevance:This study emphasises the importance of exercising endoscopic evaluation in nonracing performance horses with abnormal respiratory noise and/or poor performance for accurate assessment of dynamic upper airway function.
SummaryDetomidine, given intravenously at doses of 5 to 30 (mean 13) μ/kg bodyweight (bwt), provided adequate sedation for a variety of clinical procedures in 93 per cent of administrations, and improved the ease of handling in the remaining animals. Side effects of ataxia and bradycardia were minimal at the lower dose rates. Higher doses were required for intramuscular use. In experimental trials 10 and 20 μg/kg bwt resulted in deep sedation and also significant hypertension and bradycardia of over 15 mins duration. Current literature on the use of detomidine in horses is reviewed.
SummaryThe aim of this study was to investigate the effect of gonadotrophin‐releasing hormone (GnRH) immunisation on mature stallions that had been used for breeding. Four Standardbred stallions were used in the study: 3 experimental animals and 1 control animal. Semen was collected regularly, i.e. twice/week, during the 4 months prior to the experimental period. The stallions were immunised against GnRH with a GnRH‐BSA conjugate. Equimune was used as the adjuvant. The stallions were immunised on 5 occasions, 4 at 2 week intervals, and the fifth 4 weeks after the fourth. Blood samples were taken once a week for analysis of GnRH antibody titre and every third week for testosterone and oestrone sulphate analyses. Semen was collected once a week, and libido and sexual behaviour were observed. Ejaculate volume, sperm concentration, total number of sperm in the ejaculate, sperm motility and sperm morphology were evaluated. Testicular size was measured once a week. At the end of the study, the stallions were castrated, and a histological examination of the testes performed.All immunised stallions produced antibodies against GnRH, and plasma testosterone concentration decreased. However, the effect of immunisation varied between stallions. In 2 of the stallions, high levels of antibodies were found, while in the third, the level was moderate. Four weeks after the first immunisation, a decrease in libido was observed. Two months after the first immunisation, marked changes in semen quality were observed in the 2 stallions with high antibody titres. Fourteen weeks after the first immunisation, the total number of sperm/ejaculate had decreased from >8.6×109 to<2.7×109, sperm motility from >59 to<10% and the frequency of morphological normal spermatozoa had decreased from >60 to<14%. The dominating abnormalities were abnormal head shapes, proximal cytoplasmic droplets and detached heads. In the third stallion, only slight changes in semen quality were found. No changes were observed in the control stallion.Decreases in testicular size were noted in all of the experimental stallions. Pronounced histological alterations in the testes were observed in 2 of the stallions.It is concluded that the vaccine was effective in stimulating production of GnRH antibodies and in suppressing testicular function and androgen secretion. However, there was an individual variation in the responses among the stallions and, further, libido was not totally suppressed.
Pieter A.J. Brama, Johan M. TeKoppele, Ruud A. Bank, Derek Karssenberg, A. Barneveld, P. René van Weeren
SummaryThe aim of this study was to evaluate topographical differences in the biochemical composition of the extracellular matrix of articular cartilage of the normal equine fetlock joint. Water content, DNA content, glycosaminoglycan (GAG) content and a number of characteristics of the collagen network (total collagen content, levels of hydroxylysine‐ (Hyl) and the crosslink hydroxylysylpyridinoline, (HP) of articular cartilage in the proximal 1st phalanx (P1), distal 3rd metacarpal bone (MC), and proximal sesamoid bones (PSB) were determined in the left and right fetlock joint of 6 mature horses (age 5–9 years). Twenty‐eight sites were sampled per joint, which included the clinically important areas often associated with pathology. Biochemical differences were evaluated between sampling sites and related with the predisposition for osteochondral injury and type of loading.Significant regional differences in the composition of the extracellular matrix existed within the joint. Furthermore, left and right joints exhibited biochemical differences. Typical topographic distribution patterns were observed for each parameter. In P1 the dorsal and palmar articular margin showed a significantly lower GAG content than the more centrally located sites. Collagen content and HP crosslinks were higher at the joint margins than in the central area. Also, in the MC, GAG content was significantly lower at the (dorsal) articular margin compared with the central area. Consistent with findings in P1, collagen and HP crosslinks were significantly lower in the central area compared to the (dorsal) articular margin.Biochemical and biomechanical heterogeneity of articular cartilage is supposed to reflect the different functional demands made at different sites. In the present study, GAG content was highest in the constantly loaded central areas of the joint surfaces. In contrast, collagen content and HPcrosslinks were higherin areas intermittently subjected to peak loading which suggests that the response to a certain type of loading of the various components of the extracellular matrix of articular cartilage are different. The differences in biochemical characteristics between the various sites may help to explain the site specificity of osteochondral lesions commonly found in the equine fetlock joint. Finally, these findings emphasise that the choice of sampling sites may profoundly influence the outcome of biochemical studies of articular cartilage.
J. Bézard, A. Mekarska, Philippe Monget, Guy Duchamp, E. Palmer
SummaryThe objects of this study were to monitor the development of the cumulus complex and nuclear maturation in oocytes recovered from preovulatory follicles following treatment to induce ovulation and to investigate the in vitro maturation competence of oocytes recovered from smaller nonpreovulatory follicles of varying size. All follicles ≤5 mm in pony mares were individually punctured at 0, 6, 12, 24 and 35 h after an injection of LH to induce ovulation. The recovery rates of oocytes were 64% from 55 preovulatory follicles, 22% from 32 subordinate follicles and 52% from 227 small follicles. Cumulus expansion of the preovulatory oocytes occurred at 12 h post LH treatment while the metaphase I and II components of nuclear maturation were not completed until 24 and 35 h post LH respectively. For nonpreovulatory follicles, the frequency of atresia and oocyte competence for in vitro nuclear maturation both increased with increasing follicular size.