TODAY, We Will Discuss The Use Of Prazosin for Cats

Kaylee Ferreira

Published by Dr. Kaylee Ferreira

Updated on

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What is Prazosin for Cats? 

Prazosin for cats is a medication often prescribed in treatment programs to manage urethral obstructions. The drug blocks the α1-adrenoceptors resulting in smooth muscle relaxation in the bladder and the urethra.

Veterinarians prescribe prazosin hydrochloride for cats suffering from inflammatory, infectious or obstructive forms of lower urinary tract disease. The main therapeutic aim of the drug is to relax the bladder and urethra and prevent recurrent urethral obstruction.

Devon Rex Cat with pills

What is Prazosin Used for in Felines?

What Does Prazosin Do For Cats? Prazosin’s veterinary uses include treating high blood pressure, congestive heart failure, and urethral spasms. Prazosin is an α1-adrenoceptor antagonist, which selectively and competitively blocks the contractile effect on smooth muscle receptors, resulting in relaxation and vasodilation of the smooth muscles. 

Prazosin helps alleviate symptoms but does not remedy the underlying cause or condition. Cats who suffer from lower urinary disease experience the potentially life-threatening symptoms of urethral obstruction due to mucus, urinary crystals, stones, or cellular debris that form a plug. 

A urethral obstruction is a medical emergency that needs rapid intervention by a veterinarian to unblock the cat before severe side effects endanger the cat’s metabolic stability. Once hospitalized and unblocked, some cats still struggle to pass urine due to urethral spasms. 

Vets prescribe prazosin to alleviate the symptoms of swelling and spasms after a cat has had the indwelling catheter removed. Lower urinary tract disease requires a combination of medications, prescription diets, and stress management to avoid recurrent bouts of urethral obstruction.

Some vets also use Prazosin for cats with certain cancers or traumatic spinal cord injuries if the patient cannot express the bladder independently.

Not all veterinarians agree that prazosin is an essential medication for urinary obstruction due to the risk of increased recurrence of a patient blocking after using the drug. 

The school of thought is that the feline urethra is only 28 to 37 percent smooth muscle proximally and the rest of the urethra has striated muscles. This fact means that up to a third of the urethra is unaffected by prazosin.

Most urethral obstructions occur in the distal urethra, so prazosin’s effects will not reach the area where most obstructions arise. This limitation and the stress of administering oral medication are enough for some vets to exclude prazosin for cats’ UTI treatment. 

Possible Side Effects

Any medications carry the potential to cause adverse effects, and every patient responds differently. It is essential to monitor patients starting medications to detect adverse effects early. If they seem to cause the cat any discomfort, it is best to contact the attending veterinarian immediately. 

When administering prazosin for cats, side effects may include:

  • Decreased energy levels, fatigue, and low activity levels.
  • Decreased blood pressure.
  • Weakness or disorientation.
  • Vomiting, decreased appetite, diarrhea, or constipation.
  • More serious effects that need veterinary attention include a rapid heart rate, increased temperature, hyperactivity, or anxiety

Frequently Asked Questions About Prazosin

Does Prazosin Make Cats Sleepy?

One of the adverse effects of prazosin is lethargy, which may make cats sleep more and show decreased levels of activity and interest in their environment. 

What Does Using Prazosin For Cats Long-Term Lead To?

The chronic use of α1-adrenoceptor blockers may lead to hypotension in cats. Low blood pressure may make the patient faint or have low energy levels. The regular use of prazosin has no benefit in preventing recurrent urethral obstructions.

Why are Generic Versions of Prazosin So Much Cheaper Than Brand-Name Prazosin?

When companies release a drug, they spend millions of dollars on research and clinical trials. To reclaim the invested funds, companies patent the drug. The patent lasts around twenty years and prevents competitors from producing the drug with the same active ingredient. 

Companies that develop the drug charge significantly more because of the patent and the investment into clinical trials and research. 

Generic drugs go into production as soon as the patent expires. They can produce the drug with the same active ingredient without the research costs as long as it contains different inactive ingredients and looks different from the original drug. Although generics are cheaper, they may contain inactive ingredients unsuitable for cats. 

Tips for Administering Prazosin to a Feline

The prescribing veterinarian will discuss the prazosin dose and method of administration during the dispensing consult. Most details will be on the packaging, including the frequency and quantity to administer. 

The calculation of prazosin dosages depends on a patient’s weight and is ideally administered with or after a meal. Depending on the patient’s needs, dosing intervals range between twice to three times daily. 

Always wash your hands after administering any medication and store the medicine safely according to the prescription label.

Curious tabby cat sniffs on pill

How Long Does it Take to Work?

Prazosin is effective within one to two hours after administration. The drug is short-acting and stops working within twenty-four hours of the last dose. Renal or hepatic impairment may increase the duration of the medication’s effects. 

How Does Prazosin Work for Cats?

Veterinarians use prazosin for cats urinary smooth muscle relaxing effects to help relieve spastic bladders or urethras. Other medications that cause muscle relaxation do not work on the same smooth muscle receptors that prazosin does, thus making it a unique drug well suited to alleviating spastic episodes that may prevent urination.

Cats who suffer from lower urinary tract disease struggle to pass urine for several reasons when the bladder or urethra is inflamed. Some reasons include an aversion due to the pain experienced during their urinary obstruction, idiopathic spasms, inflamed lumens, and anxiety.

Prazosin helps to relax the bladder and the urethra and alleviate the discomfort cats associate with passing urine, thus enabling them to pass urine more frequently without pain and anxiety. 

It is important to note that prazosin helps provide relief of the symptoms associated with lower urinary tract conditions, spinal injuries, or cancers affecting the bladder, but it is not curative. Any cat with UTI symptoms must always have access to fresh water, increased wet food availability, litter trays away from other cats, and a prescription diet that focuses on urinary care.

Other Medication Details

Prazosin Medication Description
Medication TypeSmooth muscle relaxant and sympatholytic.
FormCompounded liquid, capsule, or tablet.
Prescription RequiredYes, a prescription is required to obtain this medication.
FDA ApprovalNo, this medication does not have FDA approval.
Life StageRecommended for use in adults or geriatric patients.
Brand NamesMinipress, Minizide, Hypovase and Pratisol.
Common NamePrazosin hydrochloride.
Available Dosage FormsCapsules and tablets occur in 0.000035, 0,00007, and 0.00018 oz (1 mg, 2 mg, 5 mg). Pharmacists compound prazosin liquid for cats on an as-needed dosage.Vets commonly prescribe prazosin HCl 1mg for cats.
Expiration RangeConsult the package insert carefully. Following the storage instructions closely.
ConsiderationsDo not use it on animals that experienced adverse reactions in the past. Not indicated for pregnant or lactating animals.

Prazosin is often prescribed and dispensed as a generic medication. Generic medications are cheaper, but it is vital to establish the reputability of the company producing the generic to ensure the product’s quality and effectiveness. 

Only a veterinarian may prescribe compounded prazosin, and the pharmacy that compounds it is responsible for providing a homogenous and stable solution that delivers the correct dose according to the prescribed recommendations of the vet. 

Possible Drug Reactions

As with any medications, it is crucial to disclose any current treatments, drugs, or supplements your cat may already be on with the veterinarian, as prazosin may react with other medications. Remember to discuss the medication amount and dosing frequency as well.

Patients should exercise caution when using prazosin if they fit the following criteria:

  • A previous history of an allergic reaction to the medication.
  • Renal disease.
  • Low blood pressure.

Clonidine decreases the effectiveness of prazosin. Contraindicated drugs that should not be administered concurrently with prazosin include beta-blockers, sildenafil, verapamil, and nifedipine. 

What Happens if I Miss a Dose?

Should an owner miss a dose, they need to give the next dose as soon as they remember, or if it is close enough to the next scheduled dose, then instead continue with the regular dose routine. Do not administer a double dose; maintain a regular dosing schedule. 

What Does Feline Prazosin Cost?

The average cost of brand-name prazosin tablets is quite expensive. The price is around $150 for a fortnight supply. 

The generic tablets or capsules range from around $15 to $25 for a fortnight’s supply. The specially compounded liquid form’s costs differ according to the dispensing pharmacy.

Drug Storage Instructions

Prazosin for cats is available in various forms. The main storage instructions to follow include storing the product at room temperature or in the fridge, away from direct sunlight, and out of reach of children and pets. 

Only administer this medication to the pet it was prescribed for, and do not use it in humans. Federal regulations decree that a licensed veterinarian only prescribes this medication.

Cat and medicine

Final Thoughts

Using prazosin in cats with lower urinary tract disease, spinal injuries, or cancer aims to alleviate the discomfort and anxiety associated with bladder and urethral spasms. 

Cats are primarily private creatures of habit that have particular litter tray needs. Ensure that cats taking prazosin have ample access to fresh water, wet food, and multiple litter trays to promote healthy elimination behavior and a speedy recovery. 

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Kaylee Ferreira


Dr. Kaylee Ferreira, a South African vet from Johannesburg, excels in diverse veterinary roles. Founder of Kubuntu Veterinary Services, she's a dedicated animal lover and adventurer.


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