Roundworms are the most common of the parasitic worms found inside a dog. Almost all dogs become infected with them at some time in their lives, usually as puppies. Roundworms may be contracted in different ways, making them easy to spread and hard to control.
Your dog may be infected with roundworms from the time it is born because often the mother passes the worms to the puppy while it is still in her body. Roundworms can also develop in a puppy after it is born when the puppy eats larvated eggs from the environment or drinks worm larvae (young worms) in the mother's milk. Another way roundworms are passed is when roundworm larvae are present in the tissues of a mouse or another small mammal and the puppy eats the animal.
Adult roundworms live in the affected dog's intestines. Many dogs do not have signs of infection; however, dogs with major roundworm infections, especially puppies, show diarrhea, vomiting, weight loss, dull hair, and a potbellied appearance. The dog may cough if the roundworms move into the lungs.
You may notice the adult roundworms in your dog's feces or vomit. They will appear white or light brown in color and may be several inches long.
Because roundworms can enter your dog's body in many different ways, it is essential to keep your dog's living area clean, remove feces regularly, and, if possible, prevent your dog from eating wild animals that may carry roundworms.
To get rid of roundworms that are passed from the mother dog, puppies should be treated at 2, 4, 6, and 8 weeks of age and then receive a preventive treatment monthly. Fecal (stool) examinations should be conducted 2 to 4 times during the first year of life and 1 or 2 times each year in adults. Nursing mothers should be kept on monthly preventive and treated along with their puppies to decrease the risk of transmission.
Many heartworm preventives also control roundworms. Ask your veterinarian about prevention and treatment choices that are appropriate for your dog.
Roundworms do pose a significant risk to humans. Contact with contaminated soil or dog feces can result in human ingestion and infection. Roundworm eggs may accumulate in significant numbers in the soil where pets deposit feces. Once infected, the worms can cause eye, lung, heart and neurologic signs in people.
Children should not be allowed to play where animals have passed feces. Individuals who have direct contact with soil that may have been contaminated by cat or dog feces should wear gloves or wash their hands immediately.