Ivermectin and Pets
Find out if Ivermectin is toxic to dogs and cats.
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Ivermectin is one of the most widely used antiparasitic drugs in veterinary medicine, but it has a narrow safety margin and can cause life-threatening neurological toxicity when dosed incorrectly. In dogs, label-dose heartworm preventives are generally safe; however, accidental ingestion of large-animal formulations, giving a large-dog product to a small dog, or using ivermectin off-label can quickly lead to overdose. The risk is dramatically higher in dogs carrying the MDR1 (ABCB1) mutation, commonly seen in Collies, Shetland Sheepdogs, Australian Shepherds, Long-haired Whippets, and related mixed breeds.
Cats are far more sensitive to ivermectin than dogs and should only receive products specifically formulated and dosed for felines by a veterinarian. Common exposure scenarios include pets chewing into livestock paste tubes, licking topical products applied to other animals, or well-meaning owners using dog or horse ivermectin on cats.
Early signs of toxicity include dilated pupils, excessive drooling, vomiting, tremors, stumbling, lethargy, and weakness. Severe cases can progress to blindness, seizures, coma, and respiratory failure. Symptoms may be delayed for several hours after exposure.
Prevention is straightforward: keep all ivermectin products, especially livestock pastes and pour-ons, out of reach of pets; use only veterinarian-prescribed products at the exact dose for your pet’s species and weight; and consider MDR1 testing for at-risk breeds before giving any macrocyclic lactone drug. Never use dog or livestock ivermectin products on cats.
Is Ivermectin Toxic to Dogs?
Safe at approved veterinary label doses for heartworm prevention in most dogs, but neurotoxic at high doses. Dogs with the MDR1 (ABCB1) mutation—including many Collies, Shepherds, and related breeds—are far more sensitive and can become seriously ill at doses that are tolerated by other dogs.
Is Ivermectin Toxic to Cats?
Cats are significantly more sensitive than dogs to ivermectin. Products labeled for dogs or livestock should never be used on cats, and even small overdoses can cause severe neurological toxicity.
Active Ingredients
- ivermectin
Common Brand Names
- Heartgard
- Ivomec
- Stromectol
- Sklice
- Soolantra
Dosage Form
tabletchewabletopical solutioninjectablepaste
Common Uses
- heartworm prevention in dogs
- treatment of certain parasitic infections
Toxic Ingredients
- ivermectin
Symptoms to Watch For
- dilated pupils
- tremors
- ataxia
- blindness
- seizures
- coma
- hypersalivation
- vomiting
- lethargy
- weakness
- respiratory distress
What If My Pet Was Exposed to Ivermectin?
Contact your veterinarian or a pet poison control center immediately if you suspect an overdose or inappropriate exposure. Bring the product packaging and note the approximate amount ingested. Do not induce vomiting unless instructed by a professional.
Sources
Vet's Note
PetPilot provides general information for educational purposes. While we reference authoritative veterinary organizations, this page has not been individually reviewed by a veterinarian for your specific pet. Individual animals may react differently based on age, weight, breed, health conditions, and amount consumed. Always consult your veterinarian or a poison control center for personalized advice, especially if your pet is ill, injured, pregnant, nursing, or on medication.