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Prazosin for Dogs and Cats

By Barbara Forney, VMD

Last reviewed: 7/13/2022

Commonly prescribed for: High blood pressure, congestive heart failure, and spasm of the urethra

Species: Dogs and Cats

Therapeutic Class: Antihypertensives

General Drug Information and Indications

Prazosin is a drug that is used in dogs and cats to treat high blood pressure, congestive heart failure, and spasm of the urethra. Prazosin causes the small blood vessels to relax (vasodilation). This makes it easier for blood to circulate, decreasing blood pressure and the work load on the heart. High blood pressure can be controlled or managed by drugs such as prazosin, but these drugs do not cure the underlying medical problem. Like many other drugs in veterinary medicine, this drug 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 pet exactly as your veterinarian prescribes. If you miss giving your pet a dose of prazosin, 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.

Prazosin should be given with food.

Wash your hands after giving your pet this medication.

Side Effects

Be sure to discuss any side effects with your veterinarian immediately.

Most side-effects occur at the beginning of treatment. They can include dizziness or even fainting when your animal first stands up. Other side effects are related to the digestive tract and can include vomiting, diarrhea, or constipation.


Keep this and all drugs out of reach of children. This drug should only be given to the animal for which it was prescribed. Do not give this medication to a person.

Federal law restricts this drug to use by or on the order of a licensed veterinarian.

Prazosin should not be used in animals with low blood pressure or those with chronic kidney problems.

Drug Interactions

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

Other drugs that lower blood pressure are generally not used with prazosin. This includes beta blockers, sildenafil, verapamil, and nifedipine.

Clonidine may decrease the effects of prazosin.


If you suspect your pet or another animal has been 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 have the prescription container with you when you take your pet for treatment.

If you or someone else has accidentally ingested this medication call the National Capital Poison Center at 800.222.1222.


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

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