Intestinal Parasite Lifecycle: Worms Within

Trifexis® (spinosad + milbemycin oxime) chewable tablet for dogs provides protection from three intestinal parasites.

Roundworm, hookworm, and whipworm are generally contracted either through ingesting the eggs or larvae, in the case of hookworm, by coming into direct contact with infected soil. In each case, the larval form of the worm migrates to the intestinal tract, where they mature into adults. The following descriptions are brief but provide a general idea of each worm's lifecycle¹.

Roundworm

Roundworm eggs are deposited into the environment in animal feces and remains. Dogs ingest infective eggs from a contaminated environment. The larvae released from the eggs mature to adult worms which cause infection in your dog.

Roundworm larval migration is complex, but generally, once inside the dog, roundworm larvae migrate through the liver and lungs. The infected dog coughs them up into her mouth from the lungs and swallows them, which allows them to move into the small intestine. (In unborn puppies, the migration from the liver to the intestines is delayed until the pups are born.)

The larvae mature into adults in the intestines, laying eggs there, which are passed through the infected dog’s waste back into the environment.

Hookworm

Hookworm eggs are passed into the environment in animal feces, where they hatch and develop until they reach the infective larval stage. This phase takes from 2 to 9 days, depending on temperature and humidity.

When a dog eats these infective larvae or comes into direct contact with infected soil or animal remains, the larvae penetrate the skin and migrate to the small intestine. (As with roundworm, the larvae can migrate to the lungs, where they burrow into the tissue and go dormant. Some hookworm larvae can remain dormant until other adult worms die or the dog becomes pregnant or infected puppies are born.)

Once in the small intestine, the larvae mature into adult worms and feed on the walls of the intestine as well as on blood sucked from them. Adult worms can live for 4 to 24 months in the small intestine¹.

Whipworm

Whipworm eggs pass into the environment through feces of infected hosts. Once deposited in the soil, they are highly resistant to destruction by environmental factors, such as temperature extremes and sunlight.

Infection occurs when a dog ingests the infective eggs. The larvae generally hatch in the small intestine and penetrate the mucous layer, where they develop for another 2 to 10 days before moving to the large intestine.

Larvae mature into adult worms in the large intestine. Signs of infection can begin appearing between 74 and 90 days from the time of infection.

Trifexis^® makes controlling intestinal parasites easy, with one monthly, chewable tablet.

Learn more about Trifexis^® — and why it might be the right intestinal parasite protection for your dog.