Castration and other factors affecting the risk of equine laminitis.

: The characteristics of a series of equine laminitis cases were compared with that of other Equidae examined at the University of Missouri Veterinary Hospital and Clinic during May, 1965 through December, 1971. The model age for ponies with laminitis was 7-9 years and for all other cases the model age was 4-6 years. Also the predominant age for mares was 4-6 years and for males was 7-9 years. After controlling for age and breed differences, there were significantly fewer castrated males among the affected males than expected (P small than 0.02), indicating that hormonal factors may play a role in laminitis. Ponies had a significantly greater risk of laminitis (P smaller than 0.001) and their relative risk was 4.3 times greater than all other Equidae combined. There were more laminitis cases diagnosed during May than during other months.