Side Effects Of Heartworm Medicine In Dogs. Dogs that have been under heartworm prevention may develop hind leg paralysis. Some dog owners report that their dogs experience mild or brief side effects after taking heartworm medication.
Here are some reported side effects of common heartworm medications for dogs. Some of the side effects of ivermectin include: In the case of an allergic response to the heartworm medication, a dog may experience itching, hives, swelling of the face, or even seizures or shock.