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Pergolide for Horses

By Barbara Forney, VMD

Last reviewed: 7/13/2022

Commonly prescribed for: Equine Cushing's Syndrome

Species: Horses

Therapeutic Class: Dopamine Agonist

General Drug Information and Indications

Pergolide is the drug of choice to treat the most common endocrine disease of older horses and ponies. This disease is called Equine Cushing's syndrome. The scientific name is pituitary pars intermedia dysfunction. Equine Cushing's syndrome is caused by decreased production of an important chemical messenger called dopamine. People with Parkinson's disease also have decreased dopamine levels and pergolide was used to treat Parkinson's disease until 2007. The FDA withdrew pergolide from the human market due to cardiac complications seen in some human patients. These problems have not been seen in the horse.

Equine Cushing's syndrome is a medical problem that is managed but not cured. The majority of horses with Equine Cushing's syndrome will have significantly improved quality of life while being treated with pergolide.

There is another similar endocrine problem in horses referred to as Equine Metabolic Syndrome. Although these animals may have some of the same clinical signs as horses with Equine Cushing's syndrome (particularly obesity, laminitis, enlarged fat pads and a cresty neck), this is probably a separate endocrine disease and is not as likely to respond to treatment with pergolide.

Like many other drugs in veterinary medicine, pergolide is not FDA approved for use in animals and is not available from a veterinary pharmaceutical manufacturer. Instead, it is compounded by a specialty pharmacy.

How to Give this Medication

Give this medication to your horse exactly as your veterinarian prescribes. If you miss giving your horse a dose of pergolide, give the next dose as soon as you remember or, if it is close to the next scheduled dose, return to the regular schedule. Do not double dose to catch up.

Wash your hands after giving your horse this medication.

Side Effects

Be sure to discuss any side effects with your veterinarian immediately. Pergolide is generally very well-tolerated by horses.

The most common side effect is a decrease in appetite at the beginning of treatment. This may be managed by stopping treatment for a few days and then restarting treatment at one-half the dose, gradually increasing to the full dose.

There are a number of side effects that have been documented in humans that may be possible in the horse but are not commonly reported. These include agitation, hallucinations, irregular heartbeat, low blood pressure, and twitching.


Keep this and all drugs out of reach of children. Pergolide is a prescription drug and should be used according to your veterinarian's directions, and given only to the animal for which it was prescribed. Do not give this medication to a person.

High doses of pergolide have been tested in laboratory animals without causing detectable harm to the fetus. This work has not been done in horses.

Pergolide has been used in pregnant mares but no formal studies have been performed. Should your veterinarian prescribe pergolide for use in a pregnant mare, the mare will need to be withdrawn from pergolide prior to her due date in order to establish a normal lactation. It is not known if pergolide is excreted in milk but this type of drug may interfere with lactation. Breeding a mare with pre-existing hormonal problems is more difficult and may carry greater risks.

No information is available about pergolide use in breeding stallions.

Drug Interactions

Be sure to review with your veterinarian any medications or supplements your horse may be receiving.

Acepromazine and other similar tranquilizers may interfere with the action of pergolide.


Some of the compounded forms of pergolide are available as a "treat." It is important to be aware that these are medications and should only be given in the prescribed dose.

If you suspect your horse or another animal was accidentally overdosed or has eaten this medication inadvertently, contact your veterinarian or the A.S.P.C.A.'s Animal Poison Control Center at 888.426.4435. Always bring the prescription container with you when you take your horse for treatment.

If you or someone else has accidentally ingested this medication call the National Capital Poison Center at 800.222.1222. Overdose in humans causes gastrointestinal upset and hallucinations.


Different strengths or dosage forms of pergolide may have different storage requirements. Read the labeling or ask your pharmacist for the storage requirements of the prescription you receive.

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