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Roundworm Infection

May 14, 2019 | Cats, Disease and Symptoms, Pet Care

Roundworms are one of the most common intestinal parasites of cats and dogs. They are parasites that reside in the small intestine and are contagious through contact with infected feces.

Life Cycle

Eggs are passed through the feces of a dog or cat with roundworm. The pre-patent period of roundworms is 6 weeks. This means that roundworm eggs need to sit in the environment for 6 weeks before they can become infective. The eggs will sit in the environment until they are either consumed by another dog or cat, a human or an intermediate host (i.e. a mouse). The eggs will then mature into adult roundworms and remain in the small intestines of the animal. This is where they will stay and release eggs that will eventually end up in the feces.


Clinical Signs – Pot-bellied appearance, diarrhea, coughing (if the worms have migrated into the lungs) and visible worms in the stool

Fecal Flotation – If you or your veterinarian are concerned that your pet may have roundworms, a stool sample will be required to perform an in-house fecal flotation. A roundworm diagnosis will be confirmed if eggs are visible in the feces under the microscope.

Treatment & Prevention

It is assumed that all puppies are infected with roundworm because it can be passed to them via their mother’s milk or transplacentally. Young animals are prophylactically sent home with an oral dewormer between their first few vaccine appointments. When an older animal is diagnosed with roundworm, a dewormer is sent home at that time.

Many heartworm prevention products also prevent against intestinal parasites. Therefore, your pet will be protected against roundworm infection during the spring/summer/fall months when they are taking these heartworm products.


Roundworms are zoonotic, meaning they can infect humans as well. Roundworms do not complete their life cycle in humans, they remain in the larvae stage. The larvae can migrate to damage the eyes and/or organs. It is important for owners to pick up their dogs’ feces immediately and wash their hands after to reduce the risk of roundworm transmission. Also, precautions should especially be taken with young children. Year-round deworming is recommended for pets living with young children.