The best dog dewormers kill parasites such as tapeworms, roundworms, and hookworms.Chewy/Business Insider Intestinal parasites, often called worms, are microscopic organisms that live inside your dog ...

Heartworm -- a worm that can take up residence in a dog’s heart, blood vessels, and lungs-- might seem like an unlikely threat to your pet. But it’s not uncommon.: It's been found in all 50 U.S.