Skip to main content


There are many types of roundworms, but some of the most common are intestinal parasites of dogs, cats, and raccoons.  Puppies and kittens are frequently infected with roundworms. Puppies get them from mom either before birth or through mom’s milk. Kittens can be infected via the mother’s milk. Dogs and cats can also contract the worms through the ingestion of eggs or infected “hosts” like rodents, rabbits and birds.

Adult roundworms are ivory colored, four to six inches long, and round in shape.  These parasites can cause diarrhea, vomiting, weight loss, and even coughing in animals that have them. Usually, you won’t see the adult roundworms passed in the stool.  This is why it is important for us to do a laboratory test to check for any parasite eggs that might be present. You should bring a fresh stool sample (one that was produced that day) to your animal’s appointment, and we will check for these eggs with a microscope. We recommend at least two stool sample checks on every puppy or kitten, and at least one test per year on adult pets.

It is important to know that animal roundworms can be transmitted to people, and in some cases can cause serious disease. Although most people who are infected with roundworms have no symptoms, the parasite is capable of causing blindness (especially in children) and other systemic illness.  The infective agent is the microscopic egg in the animal’s stool.

The most dangerous roundworm is Baylisascaris, a parasite of raccoons that has an affinity for brain tissue. Children infected with this parasite have suffered severe, permanent mental retardation.  The majority of raccoons carry this parasite.  If wildlife is present on your property, you should patrol the grounds and any raccoon stools should be treated as hazardous waste.  Wear disposable gloves and double bag the waste and dispose of the feces.

Roundworm can be treated with a simple deworming medication given orally. The key is to prevent reinfection by cleaning up feces in the yard daily. Many heartworm preventives also control roundworm infection.

The CDC recommends regular deworming of all puppies and kittens to try to reduce the exposure to people. A medication will be dispensed when your puppy or kitten is first seen.  Another important measure is monthly heartworm preventative, which is also effective for preventing roundworms, and an important part of a wellness program.

The CDC recommends the following prevention measures:

  • Keep dogs and cats under a veterinarian’s care for early and regular deworming
  • Clean up after the pet and dispose of stool daily
  • Keep animals’ play area clean
  • Wash hands after playing with dogs or cats
  • Keep children from playing in areas where animals have soiled
  • Cover sandboxes to keep animals out
  • Don’t let children eat dirt