The drug works by stimulating alpha-adrenergic and beta-adrenergic receptors in a dog’s body leading to the release of norepinephrine, which in turn improves the urethral closure pressure.
Note: Do not give Proin or any other medicines containing phenylpropanolamine to your dog without approval from your vet.
A typical dosage of Proin for treating incontinence in dogs is 0.91 mg/lb every 12 hours, but up to 22.7 mg/lb every 8 hours may be recommended for urethral sphincter hypotonus. When the medicine is used to treat retrograde ejaculation a range of 1.4 – 1.8 mg/lb may be used instead. Always follow the exact recommendation of your vet.
Effects may take several days to kick in, and missed doses are likely to reduce the drug’s effectiveness.
Proin is available as 25, 50 and 75 mg tablets which are scored down the middle for easy splitting. Buying larger tablets and splitting them in half will work out cheaper in the long run.
Is It Safe?
Some owners are concerned about the risk of stroke, but this seems to be rare, particularly in healthy dogs. Strokes following the use of phenylpropanolamine are probably linked to the raise in blood pressure the drug can cause, which would put dogs with heart disease or hypertension at the most risk. We recommend speaking to the vet about this if it worries you. You should also check out this page on Snopes.com which contains information about the PPA warning issued by the FDA.
Aside from a possible increase in the risk of stroke, there are some dogs who must be monitored carefully during treatment. This includes those with the following medical conditions:
- Diabetes mellitus
- Heart disease
- High blood pressure
- Prostate enlargement
There are also several drugs which could interact with phenylpropanolamine including MAOIs (e.g. Calming Collar), NSAIDs, other sympathomimetic drugs and some antidepressants. It should not be given to dogs before they receive a gaseous anaesthetic.
Pregnancy: It appears to be safe for use during pregnancy, but may lead to decreased ovum implantation.
We recommend the following guidelines to use this drug safely:
- Do not use without veterinary approval
- Discuss the stroke risk with your vet if you are concerned
- Notify the vet of any medical conditions your dog suffers with
- Take steps to reduce the weight of your dog if they are overweight
- Notify the vet of any other medicines or supplements you are giving to your dog
- Provide plenty of water during treatment
Blood pressure readings should be routinely monitored during treatment to make sure they don’t raise too high.
Contact the vet if incontinence increases, or if your dog experiences changes in behavior including restlessness and anxiety which do not resolve with time. Helping an overweight dog lose weight is not necessary for treatment but is a good idea as excess weight can contribute to incontinence.
What Is It Used For?
Here are some of the side effects your dog may experience during treatment with phenylpropanolamine:
- Decreased appetite
- Increased blood pressure
- Increased heart rate
- Increased thirst
- Urinary retention
- Weight loss
- Allergic reaction
Changes in behavior (such as anxiety and restlessness) should subside with continued use. Contact your vet if behavioral changes persist or if any other side effects occur.
If your dog develops urine retention and is unable to urinate, seek immediate veterinary attention, as this can become dangerous.
Mild overdoses of Proin usually only cause an increased likelihood of the most common side effects, but large overdoses could lead to hypertension, heart problems and coma. In cases of a phenylpropanolamine overdose call your vet or the ASPCA Pet Poison Helpline on 800-213-6680 immediately.
Dr. A Fontbonne
Plumb’s Veterinary Drug Handbook (sixth edition)
PRN Pharmacal (manufacturer)