Please check the link below and keep up with the latest recalls on both dog and cat food.
Some breeds of dogs are more sensitive to certain drugs compared to other breeds. For example, Collies, Shetland Sheepdogs, Australian Shepherds and other breeds are often more sensitive to the antiparasitic drug, ivermectin [found in HeartGuard].
Dogs with the mutant gene can not pump some drugs out of the brain as a normal dog would, which may result in abnormal neurologic signs [i.e., SEIZURES]. The result may be an illness requiring an extended hospital stay--or even death.
Our Sheltie Vet recommends Interceptor or Sentinel.