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Phenylpropanolamine (Proin) Side Effects in Dogs

Phenylpropanolamine Side Effects in Dogs

If your dog was recently put on phenylpropanolamine (brand name Proin), you may be wondering about Proin side effects in dogs. Proin is a drug that is prescribed for urinary incontinence in dogs. Urinary incontinence is often seen in elderly dogs and can predispose dogs to accidents and even annoying urinary tract infections. By tackling the underlying cause for these inconveniences, old dogs are offered a better quality of life and dog owners can clean up less messes. As with many other drugs, Proin side effects in dogs are a possibility and something to be aware of.

Proin for Dog Incontinence

As dogs age, they are prone to urinary incontinence because of decreased urethral sphincter tone. If your older dog is having accidents around the home or is leaking urine drops, there's no point to punish her: this form of urination is totally involuntary and most likely, your dog is upset about it as you are.

To better understand dog urinary incontinence, imagine a leaky valve. When all goes well, there are no leaks whatsoever, when there are leaks, it is therefore due to some altered mechanism that is not working as it should. Urination in dogs is the coordinated action between the dog's nervous system and central control centers.

When a dog presents with urinary incontinence, it is therefore important that the vet rules out any medical disorders such as intervertebral disc diseases or potential neurological problems. It's therefore important that the vet conducts a neurological exam in any dogs presenting with urinary incontinence.

The diagnosis of urinary incontinence due to Urethral Sphincter Mechanism Incompetence (USMI) is a condition that is diagnosed by exclusion, after other important potential causes have been ruled out.

This condition is particularly common in large breed dogs such as Rottweilers, Dobermans, Old English sheepdogs and it especially affects spayed females. Obese dogs or dogs with a docked or bobbed tail are more predisposed. The leakage often occurs when the dog is relaxed as when the dog is walking, resting or sleeping.

Mode of Action 

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Phenylpropanolamine, brand name Proin, is also known as norephedrine. Its mode of action is similar to epinephrine (adrenaline), a neurotransmitter of the central nervous system.

How does Proin work in dogs? This drug increases muscle tone in the dog's urethra preventing any urine from leaking out. The urethra is simply the tube that carries the dog's urine from the bladder to the outside. Because nerves are responsible for creating muscle tone, Proin works as a nervous system stimulant. It helps with the decreased estrogen levels as seen in female dogs.

Treating urinary incontinence is important for dogs. It's not only a matter of inconvenience cleaning up urine drops left around the house. Dogs affected by urinary incontinence are more prone to annoying urinary tract infections.

This is because dogs suffering from lack of muscle tone also lose some of their normal defenses meant to prevent bacteria from accessing the urinary tract. It is therefore recommended to have an incontinent dog's urine checked twice a year for possible infection, suggests veterinarian Dr. Weis DVM.

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Because the dog's body has many wide-spread receptors, phenylpropanolamine affects many systems and this is also a reason why this drug can also cause several unwanted side effects.

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Proin Side Effects in Dogs 

As with other medications, the use of Proin in dogs is not without side effects. The most common Proin side effects in dogs include elevation in heart rate and blood pressure, excitement and restlessness. Dogs may act as if they had a couple cups of coffee. It's not unusual therefore to see affected dogs panting.

Because of these side effects, Proin should not be used in dogs suffering from heart disease, dog liver disease, kidney insufficiency, high blood pressure, glaucoma, or diabetes.

Other side effects may include nausea, drooling, vomiting, loss of appetite, diarrhea. Some dogs may also develop changes in skin color, with the skin becoming bright pink. In some cases, Proin can cause seizures (this product was taken off the market from use in humans due to risk of stroke albeit no "known" correlation with stroke was found in dogs), abnormal gait, elevated liver enzymes, kidney failure, and even stroke ad death (eg. dog vocalizing and then collapsing) in dogs. In older dogs a better option may be estrogen. Consult with your vet for advice.

How long does the effect of the medication last? The half life of Proin in dogs (basically, the time it takes for a drug to lose half of its pharmacologiceffect) is expected to be around 4 to 7 hours, but the effects may be seen for as long as 8 to 12 hours and sometimes as much as 24 hours in some dogs, explains veterinarian Dr. Michael Salkin. 

"For older dogs, I think the estrogen is safer than the Proin... When my old crippled greyhound, with heart and kidney disease became incontinent, I did not even consider putting her on Proin, because her risk of stroke was higher than the average dog. She did great on estrogen the last two years I had her, and was happy because she could sleep on my bed again."~Dr. Rebecca, veterinarian

How Long Does it Take for Proin To Work?

If your dog is suffering from side effects of Proin, you may be wondering how long it takes for Proin to work. Generally, this medication takes about 5 to 10 days to see full results, explains veterinarian Dr. BJ Hughes.

It is therefore important to inform your veterinarian about any side effects you see from the use of Proin.

If Proin side effects in dogs are mild, the vet may suggest to give half a dose to try and see if it reduces the side effects yet still works in reducing leakage, but if the side effects are significant, the vet may decide to put the dog on a different medication.

An alternate option may be estrogen-type products such as diethylstilbestrol (DES) or estriol (Incurin) for estrogen-responsive urinary incontinence in spayed female dogs. Consult with your vet for advice.

Did you know? Adverse side effects of drugs can be reported by dog owners to the FDA. Any animal drug can be reported and that includes drugs that are approved or not approved by FDA. Here are instructions on how to report them: How to Report Animal Drug Side Effects and Product Problems


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