Roundworms are a common intestinal parasite in dogs.

  • Puppies may be infected in utero (before birth) as worms cross the placenta from the mother to the puppy. These puppies are born already infected with roundworms.
  • Puppies can become infected after they are born by ingesting infected milk or by consuming parasite eggs from the environment.
  • Dogs can also be infected by roundworms when they eat mice or other infected mammals.

How will roundworms affect a dog?

Adult roundworms live in the infected dog's intestines. Many dogs do not show symptoms of infection. However, dogs with heavy roundworm infections, especially puppies, can have symptoms such as:

  • Weight loss
  • Dull hair
  • Potbellied appearance

The dog may cough as the migrating roundworms move through the lungs.

Adult roundworms may be seen in a dog's feces or vomit. They will appear white or light brown in colour and may be several inches long.

Can roundworms affect a human?

Roundworms can pose a significant risk to humans. Contact with contaminated soil or feces can result in human ingestion and infection. Roundworm eggs may accumulate in significant numbers in the soil where pets deposit feces.

Children should not be allowed to play where animals have passed feces. Individuals who have direct contact with soil should wear gloves or wash their hands immediately.

View the life cycle of the roundworm.

View the life cycle of the roundworm

To see the life cycle of roundworms, click here.

For information on Bayer Parasite Solutions available to treat roundworms, talk to your veterinarian.