Is Atenolol (Tenormin) Safe for Dogs?
Why it’s a problem
Atenolol is a beta blocker that slows heart rate and lowers blood pressure, and larger ingestions have been reported to cause severe bradycardia, low blood pressure, and weakness. A single tablet in a large dog is usually mild, but small dogs and higher amounts carry real risk. Dogs with heart conditions are more vulnerable.
How to keep your pet safe
Keep atenolol stored away from pets, and be careful with pill organizers and travel containers. Heart medications for dogs must come from a veterinary prescription with proper monitoring.
Warning signs to watch for
Lethargy, weakness, wobbliness, vomiting, drooling; larger ingestions: very slow heart rate, collapse, pale gums, fainting, low blood pressure.
When to call the vet
Call your veterinarian or a pet poison hotline after any exposure — heart rate and blood pressure may need to be checked. Report the strength, the number of tablets, and your dog’s weight.
Common questions
My dog ate one of my Tenormin tablets — is that OK?
A single tablet is often mild in a large dog, but smaller dogs can develop dangerous slowing of the heart. Call your vet or a poison hotline for advice based on the dose and your dog’s size.
What should I watch for after beta-blocker ingestion?
Unusual tiredness, wobbliness, pale gums, or collapse — signs of a heart rate that is too slow. Any of these need immediate veterinary attention.
More medications hazards for dogs
This page is general educational information, not a substitute for professional veterinary advice. Every pet is different — if your animal ate or touched something concerning, contact your veterinarian or a pet poison hotline right away. In the US: Pet Poison Helpline (855) 764-7661, ASPCA Animal Poison Control (888) 426-4435 (fees may apply).