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Pergolide for Veterinary Use


by Barbara Forney, VMD


Overview

Therapeutic Class
Dopaminergic agonist

Species
Horses

May Be Prescribed by Vets for:
Pituitary pars intermedia hyperplasia, "pituitary adenoma."

Search for Available Dosage Forms 


Basic Information

Pergolide is a human drug used to treat Parkinson's Disease. Pergolide is the drug of choice to treat pituitary pars intermedia hyperplasia or equine Cushing's Syndrome (ECS) in horses. Pergolide works by binding with drug receptors in the brain that control the production of dopamine.

Ask your vet these questions about compounded medications.

Cyproheptadine is another drug that has been used to treat ECS although recent work indicates that it is not very effective and that pergolide is clearly the treatment of choice.

Horses

For many years, pituitary pars intermedia hyperplasia was called pituitary adenoma. In most cases, this commonly seen condition of older horses and ponies is caused by hyperplasia or hypertrophy of the pars intermedia rather than tumor. Although the hyperplasia eventually may progress to adenoma formation, that is considerably less common. The average age of horses diagnosed with ECS is 20 (range seven to 42). Ponies may be affected more commonly. Pituitary pars intermedia hyperplasia is a medical problem that is managed, not cured. Animals that are being treated usually are on medication for the rest of their lives.

Clinical signs associated with ECS include hirsutism, polyuria, polydypsia, abnormal fat deposition, abnormal sweating patterns, laminitis and decreased immune competence. Horses usually are started on a low dose of pergolide (0.5 mg/day) and re-evaluated by six weeks. If there is no improvement, the dose should be increased gradually (by 0.25 mg) until improvement is seen. Recent work reported by J. Beech at the 2003 AAEP suggested that some horses may require higher doses than those that are used commonly.

A possible differential diagnosis for ECS is the recently hypothesized Peripheral Cushing's Syndrome (PCS). PCS is thought to be a different endocrine disturbance although there are some similar symptoms. Horses with PCS are overweight with cresty necks, abnormal fat distribution and frequently suffer from laminitis. They are not hirsute and do not respond to pergolide.

Pergolide Side Effects

  • Decreased appetite during the first week of treatment is the most commonly reported side effect of Pergolide. This may be managed by an initial reduced dose followed by a gradual increase.
  • A number of side effects are listed in humans taking pergolide with other medication for Parkinson’s Disease. Side effects included low blood pressure, headache, GI upset, anemia, respiratory infections, dizziness and hallucinations.

Precautions

  • It is important to identify and use the lowest possible dose of pergolide. Based on information from human Parkinson’s Disease patients, there is some thought that this condition may, over time, become resistant to medication.
  • High doses of pergolide have been tested in laboratory animals without causing detectable harm to the fetus but this work has not been done in horses. It is not known if pergolide is excreted in milk but this type of drug may interfere with lactation. No information was found on pergolide use in breeding stallions. Pergolide should be used only in pregnant or lactating animals if the benefits outweigh the risks.

Drug Interactions

Phenothiazine tranquilizers such as acepromazine may interfere with the action of pergolide.

Overdose

Overdose in humans causes gastrointestinal upset and hallucinations.
More Pergolide information
 

About the Author

Dr. Barbara Forney is a veterinary practitioner in Chester County, Pennsylvania. She has a master's degree in animal science from the University of Delaware and graduated from the University of Pennsylvania School of Veterinary Medicine in 1982.

She began to develop her interest in client education and medical writing in 1997. Recent publications include portions of The Pill Book Guide to Medication for Your Dog and Cat, and most recently Understanding Equine Medications published by the Bloodhorse.

Dr. Forney is an FEI veterinarian and an active member of the AAEP, AVMA, and AMWA.

You can purchase books by Dr. Forney at www.exclusivelyequine.com

The information contained on this site is general in nature and is intended for use as an informational aid. It does not cover all possible uses, actions, precautions, side effects, or interactions of the products shown, nor is the information intended as medical advice or diagnosis for individual health problems or for making an evaluation as to the risks and benefits of using a particular product. You should consult your doctor about diagnosis and treatment of any health problems. Information and statements have not been evaluated by the Food and Drug Administration ("FDA"), nor has the FDA approved the products to diagnose, cure or prevent disease.

Wedgewood Pharmacy compounded veterinary preparations are not intended for use in food and food-producing animals.