Pituitary Pars Intermedia Dysfunction (PPID)

Description: Also known as Cushing’s disease, PPID is caused when the pituitary gland produces excess amounts of adrenocorticotropic hormone (ACTH). Elevated ACTH levels, in turn, lead to overproduction of the hormone cortisol. PPID is common in older horses: One study showed that 85 percent of veterinarians are caring for at least one horse with PPID.

Signs: Excess hormones cause a slew of systemic signs including a long haircoat that is slow to shed, muscle weakness, compromised immune function and susceptibility to infection. Horses with PPID are also prone to slow-onset chronic laminitis that can go undetected until hoof structures have been irreversibly damaged.

Treatment: PPID can be controlled with the medication pergolide, sold under the brand name Prascend. Pergolide works by binding with receptors in the brain that control the production of dopamine, decreasing the blood levels of ACTH. The medication is given daily and is very effective in reducing the signs of PPID.