When people talk about worms in dogs, they are referring to certain types of internal dog parasites. What Are Worms, and How Are They Harmful? If you understand the risks, symptoms, and treatment options for worms in dogs, you can better protect your dog and your family from infection. Part of being a responsible dog owner is keeping your dog healthy and parasite-free. Puppies can even be exposed before they’re born. But unfortunately, worms are a common health risk for dogs. Just the sight of the disgusting critters is enough to make you squirm. Nobody wants to think about their dog having worms.