What is Phenylpropanolamine Poisoning?
PPA affects the central nervous system by stimulating the alpha-adrenergic receptors, which affect the smooth muscles throughout the body. Some of those smooth muscles are the brain, heart, lungs, skin, bladder, kidneys, and gastrointestinal system. An overdose of PPA can cause any of these organs to malfunction, causing heart attack, stroke, or sudden death. It is important to note that your dog’s symptoms can quickly go from barely noticeable to serious and life-threatening. Dangerously elevated body temperature, rapid heart rate, and seizures can happen in minutes, and getting your dog to a medical professional immediately is essential to saving his life.
Phenylpropanolamine, or PPA, was previously used as a decongestant for humans but was banned in the United States in 2000 because of evidence it caused risk of stroke in women. However, many veterinarians still prescribe PPA to help with urinary incontinence in dogs. It is mostly given to large breed female dogs, who have incontinence issues following medical procedures such as sterilization. This drug is absorbed quickly when given orally, and the effects last for many hours after dosing, which may cause increased blood pressure, nervousness, dizziness, and stroke in some dogs. If your dog gets a higher dose than he is supposed to, call your veterinarian or visit your local animal hospital or clinic. Even if your dog is not showing any symptoms, this can become a life-threatening emergency quickly.
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Symptoms of Phenylpropanolamine Poisoning in Dogs
The symptoms of PPA are varied depending on the amount your dog ingested, body weight, general health, and age. If your dog is over 10 years old and not in good health, any amount of PPA toxicity can be fatal quickly. However, if your dog is a young and healthy large breed dog, and he ingested a large amount (more than .6 mg of PPA per pound of body weight), you may only notice a few signs, such as nervousness, diarrhea, and high body temperature. The most common signs of PPA poisoning are:
- Abnormal heart rate
- Central nervous system stimulation
- Cerebral hemorrhage
- Dilated pupils
- Fast heart rate
- Gastrointestinal upset
- Heart attack
- High blood pressure
- Irregular heartbeat and palpitations
- Loss of appetite
- Memory loss
- Muscle injury
- Nausea and vomiting
- Pale gums
- Tremor or twitching
Causes of Phenylpropanolamine Poisoning in Dogs
- Ingestion of pet medication containing PPA
- Accidental overdose of pet medication containing PPA
Diagnosis of Phenylpropanolamine Poisoning in Dogs
Diagnosing your dog for PPA poisoning should be quite simple. If you noticed that your dog ate some medication that contains PPA, bring the medication box with you when you take your dog to the veterinarian or animal hospital. This can help your veterinarian diagnose PPA poisoning and estimate how much your dog has consumed. This is important to your dog’s treatment because the amount of PPA in your dog’s bloodstream plays a big part in creating a treatment plan.
Your veterinarian will do a physical examination, checking your dog’s blood pressure, heart rate, oxygen level, respiration rate, body temperature, reflexes, and weight. They will get some blood from your dog to perform different tests, such as a complete blood count (CBC), urinalysis, and a biochemical panel to look for decreased glucose levels, electrolyte levels, and elevated creatine levels. A blood gas profile will be done to check pH, potassium, chloride, and sodium levels. They may also do a liver enzyme screening and coagulation test to determine blood clotting capabilities. A drug screen can tell the veterinarian how much of the drug is still in your dog’s system to help choose a plan of action.
Radiographs (x-rays) of the abdomen and chest will be done to check intestinal tract, stomach, and kidney appearance. An electrocardiogram (ECG) and echocardiography (echo) may also be performed to get a look at how well the heart is working.
Treatment of Phenylpropanolamine Poisoning in Dogs
The most important part of treatment is to remove the body of any PPA left in the system by causing your dog to vomit. A charcoal lavage will be done so the PPA left in your dog’s system to stick to the charcoal and be expelled without further damage.
Certain medications, such as glucose for hypoglycemia, sodium bicarbonate to balance pH, and antibiotics to prevent infection will be administered by IV, along with fluids and oxygen therapy. If your dog’s heart rate is high, beta-blockers, such as propranolol, will be given and phenobarbital to control seizures and tremors. Acepromazine may also be useful in controlling agitation and hyperactivity. The veterinarian will keep your dog overnight for observation, fluid therapy, and to provide supportive care if needed.
Recovery of Phenylpropanolamine Poisoning in Dogs
Once your dog is stable, you can take him home, but continue to observe him for any signs of toxicity. Monitor his urine output for signs of kidney failure, which can be a complication in some cases. A follow-up appointment may be necessary to check vitals and bloodwork. Be sure to follow your veterinarian’s instructions and keep medication out of your dog’s reach to prevent this from happening again.
Phenylpropanolamine Poisoning Questions and Advice from Veterinary Professionals
My 4 year old 80 lb., Rhodesian Ridgeback rescue has been on 25 mg of Proin twice daily, because he became incontinent after he was neutered. His Pupils are always hugely dilated in artificial light, but in normal sunshine and walking him on the road the pupils become normal size with a healthy looking iris surrounding it. Even when I shine a gentle flashlight into his eyes, the pupils remain huge.
What could cause this reaction difference of artificial light in contrast to natural daylight?
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Our 16 pound dog had been on 12.5 mg PPA every 12 hrs. It wasn't working so the vet increased it to 25 mg every 12 hrs. She was on that dose for 3 weeks and then had a grand mal seizure the other night. Could the PPA have caused toxicity and a seizure even though she'd been on it at that high dose for 3 weeks?
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