It’s important to study PPID in captive wild equids in order to treat them early and thereby improve their health as well as their welfare, Shotton said. Note the differences in this zebra with PPID before (above) and after (below) treatment. | Photo: Courtesy J. Moody and A. Bond

If you think pituitary pars intermedia dysfunction (PPID), also known as equine Cushing’s disease, is unique to our modern domestic horses and ponies, think again. Recent study results suggest that even wild equids can develop the debilitating metabolic disorder.

Plains zebras, Przewalski’s horses, and even onagers are susceptible to PPID—at least in captivity, said Justine Shotton, BSc, BVSc, MSc, MRCVS, veterinary services manager and zoo veterinarian at Marwell Wildlife, in Winchester, U.K.

While scientists had already reported on a case of PPID in a captive onager in 2009, Shotton and colleagues identified six further cases in two equine species in captivity. These included five Przewalski’s horses ranging from 7 to 29 years old and a 17-year-old Chapman’s zebra (a subspecies of plains zebra), living at Marwell Zoo in Hampshire, U.K. All six animals had excessively high blood plasma levels of ACTH, the hormone responsible for the disorder, which can cause abnormal hair growth, poor body condition, and laminitis, among other problems