Roundworms are common intestinal parasites of young dogs and cats. Animals can become infected while still in the uterus, by ingesting immature parasites that are present in their mother's milk, through ingesting eggs found in contaminated surroundings, or by eating a prey animal (e.g., a rodent) that contains immature roundworms.




Puppies and kittens with heavy roundworm infestations can have a pot-bellied appearance, grow poorly, lose weight, vomit, and have diarrhea. Less severely affected animals may show no symptoms at all. Roundworm larvae in the lungs can cause pneumonia. To determine if an animal's clinical signs are caused by roundworms, a veterinarian will perform a fecal flotation and microscopic examination to look for the presence of the parasite's eggs in a stool sample. In some cases, adult worms, which look like strands of spaghetti, may be visible in an animal's feces or vomit, particularly after they have been treated with a dewormer.




Many different types of medications are available that will help an animal eliminate roundworms from its body. Pet owners should closely follow dosing recommendations because giving the correct amount of the drug on an appropriate schedule is necessary if roundworms are to be completely eliminated. People, especially children, can be infected with roundworms, which typically cause eye problems and sometimes even blindness, so routine fecal examinations, deworming, and cleaning up after pets are all extremely important.


Written by: Jennifer Coates, DVM
Last reviewed: October 2, 2008