Understanding and treating PPID

Pituitary pars intermedia dysfunction, sometimes called Cushing’s syndrome, is a common hormonal disease in older horses, says Dr Mac.

- Dr Mac

Cushing’s syndrome was named after an American neurosurgeon, Dr Harvey Cushing, who described a relationship between a hormonally-linked disease syndrome and tumours of the pituitary gland in his patients. Later, it was discovered that there were other causes for the syndrome, including excessive use of corticosteroids, in both humans and dogs. When similar symptoms of adrenocorticotropic hormone (ACTH) excess were seen in horses, the syndrome was initially called Cushing’s. It was recently renamed pituitary pars intermedia dysfunction (PPID), as it is seldom the result of a pituitary tumour. Signs of PPID in horses are mainly related to hormones that are increased by excessive ACTH, for instance cortisol, which is a steroid produced by the adrenal glands. While PPID is the most common hormonal disease in elderly horses, it is almost never found in horses younger than five years old.

SIGNS OF DISEASE