Survey of equine castration techniques, preferences and outcomes among Australian veterinarians.

OBJECTIVES: (1) To collect the perceptions of veterinarians performing equine castrations in Australia on techniques, preferences and outcomes, (2) to investigate veterinarian use and experience with the Henderson castrating instrument and (3) to investigate potential associations between demographics, castration methods and techniques, and complications. DESIGN: Online survey of members of the Australian Veterinary Association's Special Interest Group, Equine Veterinarians Australia (EVA). METHODS: A link to the survey was included in the EVA e-newsletter and practices on the EVA website were contacted by telephone and follow-up email. Fisher's exact test was used to determine associations between ligation and complications. A generalised linear model with a negative binomial family was used to determine associations between count response variables and categorical independent variables. RESULTS: Responses were obtained from 138 veterinarians (response rate, 13.1%) who performed 5330 castrations over 12 months. Castrations were most commonly performed in the field, on anaesthetised horses, using emasculators, via an open approach and without ligation of the spermatic cord. Estimated complications after use of emasculators were swelling (25%), haemorrhage (5%) and infection (5%). The Henderson instrument was used by approximately 10% of respondents and its use for castration was associated with fewer reports of postoperative swelling compared with emasculators (P = 0.002). Rates of evisceration with the Henderson and emasculator methods were comparable (0.43% and 0.9%, respectively). CONCLUSION: Castration preferences varied widely among survey participants. Reported complication types and rates were comparable to those reported previously in other countries. Perceptions that the Henderson instrument was associated with less swelling should be investigated further via a prospective controlled investigation.

Quantitative microanalysis of equine synovial fluid glycosaminoglycan concentration.

An alcian blue precipitation method for quantifying the hyaluronic acid (HA) and sulphated glycosaminoglycan concentration (SGAG) in solutions containing both compounds was assessed. The assay was found to be rapid and reliable in solutions containing 0 to 200 mg of HA/dl and 50 to 1,000 micrograms of SGAG/dl, and was not affected by the presence of protein, hemoglobin, or methemoglobin in concentrations normally found in synovial fluid. The HA and SGAG concentrations in intercarpal synovial fluid from 13 clinically normal and 11 arthritic horses were evaluated. A relationship was not found between the concentration of HA and SGAG and any other synovial fluid variable. The SGAG concentration was found to be markedly high in several of the synovial fluid samples from arthritic horses, but did not correlate with the degree of articular cartilage erosion.

Prognosis in equine colic patients using multivariable analysis.

Multiple logistic regression was used to investigate prognosis in 308 horses referred to the University of Minnesota veterinary teaching hospital with colic. Bivariate results identified the following significant individual parameters: absent or hypomotile abdominal sounds, medical or surgical classification, peritoneal fluid total protein, anion gap, serum glucose, capillary refill time, blood pH, heart rate, packed cell volume, base excess, serum chloride, plasma bicarbonate, serum urinary nitrogen and age. Two multivariable prognostic models were developed using logistic regression. Model I (based on 257 cases with a mortality rate of 39%) included age, sex, medical or surgical classification, capillary refill time, packed cell volume and heart rate. Model II (based on 138 cases with a mortality rate of 48%) included age, sex, medical or surgical classification, capillary refill time, serum bicarbonate, serum chloride and respiratory rate. Predictive performance of the models was evaluated by treating the calculated probability of death for each horse as a continuous test result. The influence of varying the probability cutoff point for death on test characteristics (sensitivity, specificity and positive and negative predictive values) was determined. These models have not been validated and thus their performance in a different population is uncertain.

Multiple recurring uterocervical leiomyomas in two half-sibling Appaloosa fillies.

Two yearling, paternal half-sibling Appaloosa fillies were ovariohysterectomized for treatment of multiple uterocervical leiomyomas. The tumors recurred in both fillies, originating from cervical tissue that could not be removed at surgery. Previously reported cases of uterine leiomyoma in the mare have been of solitary tumors in older mares that were treated successfully by surgical removal.

Neurological disease and lipofuscinosis in horses and sheep grazing Trachyandra divaricata (branched onion weed) in south Western Australia.

A severe paretic syndrome accompanied by intense neuronal lipofuscinosis is described in sheep and horses exposed to Trachyandra divaricata. This is a newly recognised toxic hazard for grazing livestock in the coastal region of the south west of Western Australia. Animals appear to become affected over a period of weeks when summer conditions induce a scarcity of alternative feed. The disease is discussed in relation to its recent documentation in South Africa where the plant is indigenous.

Radioimmunoassay of thromboxane B2 in horse plasma.

A radioimmunoassay for thromboxane B2 (TXB2) in unextracted horse plasma was evaluated. Sensitivity of the assay was 14.0 (SD 5.6) pg ml-1 of plasma. Interassay and intra-assay variation were 21.3 per cent and 4.3 per cent, respectively. The percentage of tracer bound in unextracted plasma in the absence of TXB2 was often higher than that in buffer. Therefore standard curves were obtained using standards diluted in plasma from horses treated with aspirin or in charcoal treated TXB2-free plasma. Standard curves determined in plasma and buffer were parallel. This assay was used to determine the half-life of exogenous TXB2 in horses. The mean value of 20.7 minutes (n = 3) is similar to that determined in other species. Storage of plasma samples at -20 degrees C for four months was found to alter the TXB2 levels in an unpredictable manner. Mean recovery was 102.4 per cent (SD 44.1). Effect of variability in sample collection and handling was assessed, but no consistent source of artifactual generation of TXB2 was found.

The use of the glutaraldehyde coagulation test for detection of hypogammaglobulinaemia in neonatal foals.

The effectiveness of the glutaraldehyde coagulation test (GCT) in detecting failure to acquire colostral immunoglobulin in neonatal foals was investigated. This was achieved by comparing and correlating results from the GCT with those obtained by single radial immunodiffusion (SRID) of equine IgG. The GCT was found to be a practical, inexpensive, semiquantitative test with a high specificity and sensitivity at critical IgG levels.

Changes in the synovia after the intra-articular injection of sodium hyaluronate into normal horse joints and after arthrotomy and experimental cartilage damage.

Sodium hyaluronate was injected into normal horse joints and joints that had undergone an arthrotomy and experimental cartilage damage. The elimination half-life for hyaluronic acid in normal joints was found to be approximately 96 h. The injection caused a non-significant increase (42%) in synovial fluid protein concentration and a fall in the intrinsic viscosity of the fluid. In the arthrotomy group the synovial fluid hyaluronic acid concentration fell after surgery but it was unaffected by the injection of sodium hyaluronate. An initial rise in the intrinsic viscosity of the synovial fluid from the arthrotomy group coincided with an increase in protein concentration. However there was no significant difference between the mean intrinsic viscosity or protein concentration in synovia from the control and treated joints at any time after surgery.

A retrospective study of head fractures in 21 horses.

The clinical features of 21 horses which sustained head fractures are reviewed. There was a higher incidence of fractures in males and Standardbred horses. Surgical treatment was practical and successful in most cases when the fractures involved the bones of the jaws and the face. Fractures which involved the cranial cavity or the cranial nerves were difficult to treat and usually held a poor prognosis.

Hyaluronic acid concentration in synovial fluid from normal and arthritic joints of horses.

A method previously described was used to determine the hyaluronic acid concentration in synovia from normal and arthritic horse joints. The concentration of hyaluronic acid in the synovia from arthritic joints was found to be significantly lower than the concentration in fluid from normal joints.

A retrospective clinical study of osteochondrosis dissecans in 21 horses.

Osteochondrosis dissecans was diagnosed clinically and radiographically in 31 joints of 21 horses. The horses ranged in age from 8 months to 5 years at the time of presentation. The usual age of onset of clinical signs was 18 to 24 months. Presenting complaints included joint effusion and lameness of either gradual or sudden onset. In Thoroughbred horses, the stifle joint was the most common site of lesions and in Standardbred horses lesions occurred more commonly in the hock. In 16 of the 21 horses, the contralateral joint was radiographed and 9 of these horses had bilateral lesions. Thoroughbred horses were affected most commonly, followed by Standardbred horses. The prevalence was higher in males than females, the male: female ratio being 2.5:1.

Fractures of the distal phalanx in horses.

Nineteen cases of fracture of the distal phalanx in horses are reviewed. This represented 1.1% of the total number of horses seen at Murdoch University Veterinary Hospital (MUVH) over a 32-month period. All horses were managed conservatively. Eight horses made a complete recovery. Three are being trained again and are not lame. Four horses made a limited recovery. Two horses are still resting and one horse was killed humanely when it still showed lameness after 2 years. One horse was killed humanely after the fracture was first diagnosed.

Quantitation of hyaluronic acid in equine synovia.

An assay for the determination of hyaluronic acid concentration in equine synovia (synovial fluid) was investigated. The method involved the degradation of hyaluronic acid, using a highly specific microbial enzyme. The unsaturated tetra- and hexasaccharide products were oxidized with periodate and caused to react with thiobarbituric acid for form a chromophore which absorbed in the visible range of the spectrum. The method was precise within acceptable limits for synovia and compared favorably with the widely used carbazole method of Bitter and Muir (Anal Biochem 4:330-334, 1962). The between-assay coefficient of variation was 1.7% and the method was found to be linear to 100 microgram of hyaluronic acid. The mean value for hyaluronic acid concentration in synovia of health horses was 127 mg/100 ml.