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.
This Treatment Might be used for a horse exhibiting these signsRelated Observations
Related DiagnosesThis Treatment Might Be Used for these Diagnoses
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Consider Potential Side Effects & Complications
The most common side effect is a temporary reduction in appetite during the first week of therapy.
In a 2014 paper by Schott, side effects include low incidence of colic, intermittent diarrhea, laminitis,
Pergolide could result in reduced milk production or retained placenta in mares.
Precautions: Pregnant or lactating women should wear gloves when handling. Avoid crushing tablets to reduce exposure to airborne dust.
Consider Reasons Not To Use This Treatment
Should be used with caution in pregnant and lactating mares.
Skills I might need
Is It working? Timeframe for effect
The effectiveness of this drug is best monitored by your vet rechecking of blood ACTH levels. If a horse’s signs of PPID remain uncontrolled with use of pergolide alone, the drug dose may need to be increased. Another drug, cyproheptadine is also sometimes recommended along with this medication.
In our practice, we recommend a 30-60 day recheck after initiating pergolide therapy, in order to see how well the PPID is controlled. The pergolide dosage may need to be increased and blood values checked again in another 30 days. Insulin resistance is also common in horses with PPID. Therefore, insulin and glucose levels are often monitored too.
During the first month, some owners observe an improvement in attitude, energy level, and may not less drinking and urination. Hair coat abnormalities, muscle wasting, pot belly appearance, control of laminitis, and reduced tendency for infection are signs that are likely to improve over several months to a year.
Questions To Ask My Vet
- How can I monitor my horse's response to treatment?
- How often should I communicate my findings to you?
- How frequently should the ACTH values be rechecked?
- What other management changes do I need to make?
- Is it ok to use this product for my pregnant mare?
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