PupkeeperToxicEmergency
Dog ate ivermectin and livestock dewormers? Toxic in overdose: what to do now
Toxic in overdose. Ivermectin, often from horse or cattle dewormer, can cause wobbliness, blindness and coma; collies and other MDR1 dogs are most at risk.
If your dog ate or touched this, call your vet or a pet poison line now
United States
Poison lines in other countries: United Kingdom, Canada, Australia, New Zealand, Belgium, France, JM, PR, Singapore, Switzerland, TT, VI
Ivermectin and livestock dewormers and dogs: key facts
- Verdict
- Toxic · Emergency: get help now
- What it can do
- Wobbly walking, dilated pupils, drooling, tremors and blindness. All 7
- How fast
- Within 1-2 hours in severe cases, often 4-8 hours
- What to do now
- Call your vet or a pet poison line now. All steps
- Sources
- Geyer and Janko, Curr Pharm Biotechnol (2012), Merck Veterinary Manual. Reviewed 9 October 2026.
What should I do if my dog ate ivermectin and livestock dewormers?
- Call your vet or a pet poison line now.
- Keep the product, tube or syringe and bring it with you.
- Tell the vet your dog's breed and whether it has had an MDR1 gene test.
- Get to a vet quickly. There is no antidote, but early treatment helps.
Don't
- Don't give your dog horse or livestock dewormer.
- Don't make your dog vomit unless a vet tells you to.
Symptoms to watch for
- Wobbly walking
- Dilated pupils
- Drooling
- Tremors
- Blindness
- Weakness
- Unresponsiveness or coma
When signs appear: Within 1-2 hours in severe cases, often 4-8 hours
Why
Livestock products are very concentrated, so a dog that eats some can be badly poisoned. Dogs with the MDR1 (ABCB1) gene change, common in collies, Shetland sheepdogs, Australian shepherds and their mixes, let the drug into the brain. Heartworm preventives given at the labeled dose are safe even for these dogs.
Sources
- Geyer and Janko, Curr Pharm Biotechnol (2012): Treatment of MDR1 Mutant Dogs with Macrocyclic Lactones
- Merck Veterinary Manual: Safety of Anthelmintics in Animals
Guide reviewed 9 October 2026. Page updated 7 November 2026.
General information from the sources above, not a diagnosis. When in doubt, call your vet.