Dog Heartworm Pill Side Effects. It’s known as ivermectin toxicity and can be so severe that it could endanger a dog’s life. What are the side effects of heartworm treatment in dogs?
Treatment for heartworm can cause serious complications for your pet's health and can be potentially toxic to the dog’s body. These side effects can include vomiting, diarrhea, lethargy, and in serious cases seizures and allergic reactions. Ivermectin must not be used in the rough or smooth collie, shetland sheepdog, old english sheepdog, australian shepherd or other herding breeds or crosses including these breeds.