Pergolide is the main drug used to treat Pituitary Pars Intermedia Dysfunction, (PPID aka Cushing's Disease). In horses, PPID is caused by an age-related degeneration of the area in the brain that produces dopamine.

Dopamine normally causes an inhibitory signal in the brain. Without this signal, the pituitary gland overproduces a hormone called ACTH. High levels of ACTH causes too much cortisol (stress steroid) to be produced leading to the common signs of PPID - laminitis, lethargy, thickened hair coat or reduced shedding, excessive drinking and/or urination, muscle wasting, pot belly, and others.

Pergolide is an oral medication given daily that binds to dopamine receptors in the brain, causing decreased ACTH production by the pituitary.

Currently, Prascend® is the only FDA approved medication for treatment of PPID. It is a small, 1mg tablet. It can be given in feed, or by dissolving the tablet in water in a syringe and squirting it the mouth. Due to this, it is illegal for vets to prescribe compounded formulas.

Pergolide is not a cure for PPID, but helps to manage the signs. Treatment is usually required for life and can therefore become expensive.

WHAT TO DO

Give the medication regularly, as directed by your vet. Do not stop medication without your vet's supervision. Ensure that the horse gets all the medication.

Monitor the signs of PPID, particularly the horse's body condition, hair coat. Periodically monitor for digital pulse in the feet, and watch for lameness.

WHAT YOUR VET DOES

Your vet adjusts the dose based on improvement of the clinical signs of PPID, and the results of periodic re-testing of ACTH levels in the blood.