Association of arytenoid chondritis with equine lymphocyte antigens but no association with laryngeal hemiplegia, umbilical hernias and cryptorchidism

Associations were sought between ELA A1-A10 and W11 antigens and the presence of laryngeal hemiplegia, arytenoid chondritis, umbilical hernias and cryptorchidism in Thoroughbreds and/or Quarter Horses. No significant associations were detected between laryngeal hemiplegia and any ELA antigen in Thoroughbreds. The association between arytenoid chondritis and A9 was significant with a relative risk (RR) of 15.6 and aetiologic fraction (EF) of 0.80 in Thoroughbreds. There were apparent associations based on RR between A4 and A5 in Quarter Horses with umbilical hernias (RR = 7.5 and 6.1 respectively); however, these were not statistically significant. No significant associations were detected with cryptorchidism in Quarter Horses when the control population included both sexes. When only unaffected males were used as the control group, there was an apparent increase in relative risk with A6 (from RR = 1.7 to 4.3); however this was not statistically significant. Cryptorchidism in Thoroughbreds showed an increased relative risk with A5 regardless of whether the control population included males and females (RR = 4.1) or only males (RR = 4.7) but the increases were not statistically significant.