Parasites can be annoying at the least, and very dangerous if left untreated. Roundworms (Ascarid), hookworms, whipworms, and tapeworms are common intestinal parasites that infect almost every dog. These parasites can cause poor growth and even death. The worms are passed in egg form through a dog's feces.

Hookworms
Hookworms, like roundworms are passed in egg form through a dog's feces, however, infection can also occur as a result of larvae penetrating the skin (causing a local rash), after which they migrate through the bloodstream into the intestines. Hookworms can cause diarrhea, anemia and general poor health. Dogs may lose weight from the bloodsucking of hookworms.

Roundworms
Roundworms live and grow in a dog's intestinal tract. They can reach up to seven inches in length. Symptoms of dogs suffering from roundworms include dull coat, a potbellied appearance and diarrhea and vomiting. A heavy roundworm infestation may also produce lung damage, pneumonia and liver damage.

Tapeworm Eggs
Tapeworm eggs are spread by fleas. Puppies are particularly susceptible to intestinal parasites and may be born with them or infected from their mothers milk. The veterinarian can diagnose intestinal parasites in your dog by examining a fecal (stool) sample and recommend proper treatment. Your pet should receive periodic stool checks and deworming if needed. If you have any doubt about your pet's health, call your veterinarian.