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Roundworms ( _Toxocara canis, Toxascaris leonina_ ) are the most common intestinal parasites in dogs, particularly in puppies.
Adult roundworms live in the intestines of their hosts, consuming the host’s food. They are round, white to light brown, and several inches long, resembling spaghetti or angel hair pasta.
Adult dogs contract roundworms by ingesting larvae, typically from contaminated soil or infected prey like mice or other small mammals.
Puppies are born with roundworms, having contracted them from their mother’s uterus during gestation. Nursing puppies can also ingest larvae through their mother’s milk.
Once ingested, larvae travel to the dog’s liver. As they develop into adult worms, they move to the lungs, are coughed up, and swallowed. Adult roundworms then reside in the dog’s intestines. Their eggs are shed in the dog’s stool and develop into larvae, continuing the life cycle when another host ingests them.
Signs
Signs of roundworm infection include diarrhea, vomiting, a pot-bellied appearance, coughing (dogs may cough up or vomit worms), weight loss, and a dull coat. Many dogs initially show no signs of infection.
Diagnosis
Your veterinarian can test a stool sample from your dog for worms using a lab test called fecal flotation. Roundworm eggs are visible under a microscope if adult roundworms are present in the intestines.
Treatment
Treating roundworms requires multiple oral doses of deworming medication. This medication only kills worms in the intestines, so repeated doses are necessary for newly developing adult worms. Puppies, commonly affected, are routinely dewormed during their initial vaccines, regardless of microscopic egg presence. Note that not all over-the-counter dewormers are effective; your veterinarian will have the best medication. Also, several heartworm prevention types protect against roundworms.
Zoonosis
Humans can contract roundworms through contact with contaminated soil, potentially leading to a serious condition called Visceral Larva Migrans. Always wear gloves when handling any soil, especially that which may have come in contact with dog feces. Children are at especially high risk.
