Is Lisinopril (Zestril) Safe for Dogs?
Why it’s a problem
Lisinopril is an ACE inhibitor that lowers blood pressure, and a single tablet usually causes little more than mild lethargy in a large dog. In smaller dogs, or after several tablets, exposures have been reported to cause low blood pressure, weakness, elevated potassium, and kidney strain. Risk scales inversely with body size.
How to keep your pet safe
Keep blood-pressure pills out of reach, and be careful with purses and travel bags. Heart and blood-pressure conditions in dogs need veterinary diagnosis — never share your prescription.
Warning signs to watch for
Lethargy, weakness, wobbliness, vomiting, drooling; larger exposures: collapse, pale gums, little urine, irregular heartbeat from high potassium.
When to call the vet
Call your veterinarian or a pet poison hotline after any exposure, especially for small dogs or uncertain amounts. Larger ingestions may need monitoring of blood pressure, potassium, and kidney values.
Common questions
My big dog ate one of my blood-pressure pills — should I worry?
Often a single tablet causes mild signs in a large dog, but it is still worth calling your vet or a poison hotline for a weight-based assessment. Watch for weakness and wobbliness in the meantime.
My small dog ate two lisinopril tablets — is that serious?
Yes — small dogs are much more likely to develop low blood pressure and kidney effects. Call your vet or a pet poison hotline promptly.
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).