Roundworms, also called ascarids, are the most common internal parasites of dogs and cats. The adult worms are found in the intestine and live on gut content. They resemble spaghetti-in the appearance, being 2-3 mm thick and up to 20 cm long.

How Roundworms are Transmitted
roundworm_2Many puppies and kittens are already infected while still in the uterus or acquire the infection immediately after birth, through their mother’s milk. In addition, roundworms can be acquired from the environment, by accidentally ingesting the infective eggs in contaminated soil or by eating infected rodents.

The Life Cycle of the Roundworm
Adult roundworms live in the small intestine of dogs and cats, where they lay up to 80,000 eggs per day. These eggs are shed in the environment through the animal’s feces and, within a few weeks, an infective larva develops inside. When a dog or cat picks up the infective eggs, they hatch in its stomach and the larvae penetrate the stomach wall. They start migrating to several organs before coming back to the intestine and developing into adult, egg-laying worms. Some larvae do not go back to the gut: they remain encysted in the various organs until a stimulus such as pregnancy, encourages them to start migrating and develop to adult worms in the intestine.

Roundworm Disease
Roundworms are especially harmful to puppies and kittens. The migrating larvae can cause liver, lung and brain damage. The presence of the adult worms in the intestine leads to a gut inflammation, which affects digestion, development, and growth. Common symptoms of heavy infections include:

  • Vomiting
  • Diarrhea
  • Colic (upset stomach)
  • Anemia
  • Poor growth
  • A “pot-bellied” appearance

A heavy accumulation of roundworms in a puppy or kitten can lead to death.

Treating Roundworm Infection
Since many puppies and kittens are already infected at birth, and are continuously re-infected through their mother’s milk or through the environment, it is important to initiate the de-worming treatment when the puppies are old enough. Mothers of infected puppies and kittens should be treated concurrently. This will prevent them from developing the disease and shedding parasite eggs in the feces, thus avoiding environmental contamination. Adult dogs should be given a monthly preventative to deter transmission of these parasites throughout their lives.