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» Veterinary Session
Veterinary sessionBarrett Emily Maud Elizabeth - year 6 SZIU Faculty of Veterinary Science, Institute for Animal Breeding, Nutrition and Laboratory Animal Science, Department of Animal Breeding and Genetics Supervisors: Dr. Zöldág László, Dr.Sean Arkins This study sought to investigate the prevalence of a variety of anatomical defects, to determine heritability estimates for a selection of these defects and to investigate the effect of a variety of these defects on the racing performance in a large sample of young Thoroughbred horses presented for sale. The study population consisted of data from 13,603 pre-purchase veterinary examination certificates for three and four year old Thoroughbred National Hunt (NH) horses using the Pre-Purchase Veterinary Examination Certificates from eight years of Tattersalls Ireland’s Derby Sale, Goffs Ireland June Sale and Doncaster Bloodstock Sales Ltd. (DBS) Spring Sale (2002-2009) and seven years of Tattersalls Ireland’s August Sale (2002-2008). It was found that 73.58% of the sample population had one or more defects with 12.02% having serious defects likely to prejudice their use for racing. Metacarpal/metatarsal exostoses and tarsal plantar desmitis affected 17.11% and 19.40% of the sample, respectively, while 9.81% of the horses were found to make respiratory noises and 5.26% had recurrent laryngeal neuropathy (RLN). Age, sex and year of birth had a significant effect on the occurrence of many of the defects and panel veterinarians were significantly more likely to diagnose defects than the private veterinarians (p < 0.001). To estimate h2 values a pedigree file, three generations deep was generated and heritability (h2) estimates were estimated using an animal model. The h2 values ranged from 0.01 (±0.008) for calcaneal bursitis to 0.52 (±0.044) for price. Heritability estimates for the defects were highest for tarsal plantar desmitis (0.23 [±0.030]), respiratory noise (0.13 [±0.021]), RLN (0.10 [±0.019]) and metacarpal/metatarsal exostoses (0.10 [±0.020]). The h2 values were below 0.10 for the remaining defects. Only horses entered into the sales from 2002-2004 were examined to determine the effect of the anatomical defects on racing performance, based on four years of racing results. Sex, selling status and price realised at sale had a large effect on the racing performance of the horses in the sample. Each of the defects analyzed significantly affected the racing performance to some degree (P < 0.05). Horses with RLN were significantly less likely to race (69.4% compared to 83.6%) than those without RLN and had significantly fewer career wins (0.68+0.092 compared to 0.92+0.026) and career places (1.35+0.155 compared to 1.76+0.040) than those without RLN. They also had a significantly higher proportion of non-finished races than those without RLN (34.01%+2.147 compared to 25.29%+0.456). Overall, the results indicate that a large proportion of Thoroughbred National Hunt horses are affected by defects of some kind and that certain defects are viewed negatively by purchasers, thereby affecting the selling status and price. There was a heritable component to each of the defects and each defect was found to affect racing performance to some degree. List of lectures |