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Whipworms and Parasites in Dogs

Threadworms (Strongyloides) continued...

Threadworms are mainly a problem in puppies. Infected pups suffer from a profuse watery or bloody diarrhea that can be fatal. Pneumonia may occur as the larvae migrate through the lungs.

Treatment: The diagnosis is made by finding eggs or larvae on microscopic examination of stool, both fresh and after incubation. A five-day course of Panacur is the treatment of choice. Retreatment in 30 days is recommended. Ivermectin has also been used effectively, although it is not labeled for this purpose.

Public health considerations: Dogs can readily infect humans, and vice versa. Threadworm infection in humans is a debilitating disease accompanied by chronic diarrhea. Accordingly, infected pups must be isolated until treated and cured. Extreme care must be taken to avoid human contact with the feces of dogs infected with threadworms.

Other Worm Parasites


Pinworms are sometimes a concern to families with pets and children. However, dogs and cats are not a source of human pinworm infection, because they do not acquire or spread these parasites.


This is a disease acquired by ingesting uncooked pork containing the encysted larvae of Trichina spiralis. In humans, only a few cases are reported each year. The incidence is probably somewhat higher in dogs. Prevent trichinosis by keeping your dog from roaming, especially if you live in a rural area. Cook all fresh meat for you and your dog.


Lungworms are slender, hairlike parasites about 1 centimeter long. There are several species of lungworm that affect dogs. Capillaria aerophila is acquired by ingesting eggs or a transport host, such as snails, slugs, or rodents. These parasites reside in the nasal cavity and upper air passages, producing a mild cough. Filaroides species produce a tracheal and bronchial infection that tends to be a kennel-related problem, especially in Greyhounds.

Most dogs with lungworms have mild infections and do not show clinical signs. Heavily infested dogs (usually under 2 years of age) may have a persistent dry cough, weight loss, and exercise intolerance.

Diagnosis is based on clinical signs, a chest X-ray (not always positive), and identification of the eggs or larvae in the stool or in respiratory secretions. Bronchoscopy on a dog with a Filaroides infection may reveal small nodules in the wall of the trachea. Larvae may be seen peeking out of these growths. Treatment with Panacur (fenbendazole) is often needed for extended periods of time.

WebMD Veterinary Reference from "Dog Owner's Home Veterinary Handbook"

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