If your dog or cat has a parasitic infection, they may be prescribed Ivermectin. It is also used in heartworm prevention medications. While it is a primarily dog-safe medication, it still poses risks. Some dog breeds are born with a genetic mutation that makes them sensitive to Ivermectin. Ivermectin carries potential side effects for all types of dogs, it may even induce seizures in dogs.

Ivermectin Safety

Ivermectin is the primary ingredient in some heartworm preventive drugs. It is also used in the treatment and prevention of a wide range of parasitic diseases by causing neurologic damage to the parasite. Ivermectin is safe for most dogs when administered in the recommended dosages and under the guidance of a veterinarian. Unfortunately, some dog breeds are sensitive to Ivermectin due to a mutation in the MDR1 gene mutation. Herding breeds are more likely to have the MDR1 gene mutation. The medication can cross the blood-brain barrier and cause neurological damage in dogs that have the MDR1 gene mutation. This can also lead to death. Dogs can ingest Ivermectin by eating animal excrement that has been treated with medicine for parasite control, including sheep, horses, and other animals.

What Dog Breeds Are Sensitive to Ivermectin?

Some of these breeds are more sensitive to Ivermectin than other breeds:

Australian Shepherd

Border Collie


German Shepherd

Miniature American Shepherd

Old English Sheepdog

Shetland Sheepdog

Skye Terrier

Rule of thumb with Ivermectin treatment is: “white feet, do not treat”.

Symptoms of Ivermectin Poisoning

Symptoms of poisoning may be severe or minor. In the immediate aftermath of consumption, acute effects may begin to appear within four to 12 hours, while more gradual symptoms may take two or three days to appear. Symptoms include:






Dilated pupils

Difficulty walking

Trouble breathing


Ivermectin can cause a “shock” reaction in dogs by inducing neurological damage and potential seizures.

Treatment Options

Sadly, without aggressive treatment, Ivermectin poisoning can be lethal. You should make your pet as comfortable as possible and get immediate aid from your veterinarian. It is possible for your vet to induce vomiting or deliver activated charcoal if exposure has happened within the last four to six hours. Make sure you’re on the lookout for any secondary issues that may arise.

If your dog is experiencing Ivermectin poisoning, call Pet Poison Helpline® at (855) 764-7661 and your vet at once. Dogs suffering from Ivermectin poisoning need to be treated aggressively and quickly to increase their chances of survival.