Ivermectin Toxicity in Collies

Ivermectin is the active ingredient in heartworm medications for dogs. Unfortunately, several breeds of herding dogs including collies suffer from a condition called ivermectin toxicity, which can be fatal.

  1. Identification

    • The cause of ivermectin toxicity in collies is genetic. The gene that controls the production of P-glycoprotein is incomplete. P-glycoprotein metabolizes medications through the brain and into the bloodstream.

    Function

    • Without P-glycoprotein, drugs build to toxic levels within the brain and can cause seizures and death.

    Misconceptions

    • Although the condition is called ivermectin toxicity, the lack of P-glycoprotein affects the absorption of many drugs by affected dogs. Other drugs that can affect these dogs include loperamide, erythromycin, and acepromazine.

    Prevalence

    • Approximately 35 percent of all collies are affected by the genetic deficiency, and 45 percent of collies are carriers. Only 20 percent of collies remain completely unaffected by this genetic condition.

    Prevention/Solution

    • There is now a test available to determine if your pet is affected. The test consists of a cheek swab.