RISK-FACTORS FOR LARYNGEAL HEMIPLEGIA IN THE HORSE

Hospital data from the Veterinary Medical Data Base were obtained for January 1970 to June 1986. Data were from 18 North American veterinary teaching hospitals. Patients diagnosed with laryngeal hemiplegia were identified. In order to determine the frequency of diagnosis, statist ics were gathered for patient-years-at-risk. The independant risks of age, sex, and breed on the hospital prevalence were determined. Laryng eal hemiplegia was diagnosed in 2798 horses representing 29 breeds. Th e male risk compared with females (OR = 1) was 2.7. Laryngeal hemipleg ia was diagnosed significantly more often in three breeds of draft hor ses, Thoroughbreds, and American Saddlebreds; and significantly less o ften in Arabians, Appaloosas, American Paints, and American QuarteT Ho rses. Standard bred horses and Tennessee Walking Horses were seen abou t as frequently as they were represented in the hospital population. U sing the proportion of cases-to-population seen at 2-3 years of age as the standard reference point (OR = 1), Thoroughbreds showed a peak ho spital prevalence at 2-3 years of age; thereafter their cause specific accession rate decreased. Other breeds, particularly the draft horses , showed an increasing rate of diagnosis over 3 years of age. The peak age of diagnosis for draft animals was 7-9 years; for the Standardbre d and the American Quarter Horse, it was 4-6 years.