Pet Toxin Reference
Ivermectin
Severe
Act now: If ingestion was recent, contact a veterinarian or pet poison service immediately. Do not wait for symptoms. Early treatment significantly improves outcome.
Quick Facts
Common Sources
Heartworm preventives, livestock dewormers, horse paste dewormers, mange treatments, compounded ivermectin, accidental ingestion of concentrated formulations
Highest Risk
MDR1 mutation (herding breeds), high-dose exposure, livestock/horse formulations
Category
Medications
Early Signs
Lethargy, drooling, vomiting, mild weakness
Emergency Signs
Ataxia, tremors, seizures, blindness, coma, respiratory depression, hypothermia, death
Call Your Vet
Any suspected ingestion outside prescribed dosing, especially if the product is intended for livestock or horses
Triage & Next Steps
Why this is dangerous
Ivermectin enhances inhibitory neurotransmission through GABA pathways. At normal heartworm-preventive doses it is generally safe, but at higher doses it can cross the blood-brain barrier and cause severe neurologic toxicity. Dogs with the MDR1 mutation are especially vulnerable because the drug can accumulate in the central nervous system, leading to life-threatening effects.
Go to ER immediately if
Any neurologic signs including wobbling, tremors, seizures, collapse, or extreme lethargy
What not to do
Do not attempt home remedies. Do not induce vomiting unless directed by a veterinarian. Do not give repeated doses of ivermectin without veterinary guidance.
Prevention
Store livestock and horse medications securely. Use only veterinary-prescribed heartworm preventives. Know your dog’s MDR1 status if they are a herding breed.