2015 ACVIM Forum Research Abstract Program

The prevalence of PPID was significantly (P < 0.015) greater among horses found to have 5 of the 11 clinical signs present: abnormal sweating, decreased athletic behavior, delayed shedding, loss of muscle mass, and weight loss. Although not statistically significant (P > 0.25), PPID prevalence was greater when three of the remaining clinical signs was present (excessive thirst, excessive urination, and laminitis) and was actually less when four of the remaining signs was absent (cresty neck, fat pads, pot belly, weight gain, and recurrent infections). Based on only the data on clinical signs, both delayed shedding and weight loss were found to be significantly associated with PPID status (P ≤ 0.002). Specifically, the odds of PPID among horses showing delayed shedding was four times that for horses not showing delayed shedding, and the odds of PPID among horses showing weight loss was approximately twice (1.9) among horses not showing weight loss. Based on the combined data on demographic variables, insulin levels, and all eleven interpretable clinical signs, age and insulin status were still seen to be significantly associated with PPID status, but only one clinical sign, delayed shedding, was found to be a significant predictor of PPID after accounting for age and insulin status. The odds ratio of PPID for horses showing delayed shedding (3.4) decreased only slightly after accounting for age and insulin status of the horses.