Ivermectin is one of the most commonly used heartworm prevention medications used for dogs. It is present in many different heartworm products, including Heartgard Plus®, Iverhart Plus®, Iverhart Max®, Tri-Heart® and others.
Collies and similar breeds of dogs can be more sensitive to the side effects of ivermectin than other breeds. The question arises whether the use of ivermectin in these breeds to prevent heartworm infections is safe.
Ivermectin Is Safe for All Breeds of Dogs, Including Collies and Similar Breeds, at Heartworm Prevention Dosages
Ivermectin, when dosed at the low dosage ranges necessary to prevent infection with heartworms, is generally considered to be safe for dogs of all breeds, including Collies, Shelties, Australian Shepherds and other "white-footed" breeds.
However, at higher dosages, these breeds may be more susceptible to side effects than other breeds.
Ivermectin at Higher Dosages May Not Be Safe for Collies and Similar Breeds
The increased sensitivity of individuals within these breeds to the drug ivermectin is a result of a mutation of the gene known as the MDR1 (multi-drug resistance) gene.
There is a test for this gene mutation which can be performed to determine whether an individual dog carries this gene mutation or not. If in doubt about the safety of ivermectin usage, the dog should be tested before administration of ivermectin.