Lungworm Infection

Oslerus osleri is a roundworm transmitted by direct contact and ingestion of larva. The parasite has no intermediate host and intrauterine infection does not occur. Eggs are shed in the feces or saliva. Most dogs become infected as puppies during maternal grooming or regurgitive feeding. After ingestion, the larva migrate through the intestinal wall and travel to the right atrium of the heart. From the heart, the larva enter pulmonari capillaries and alveoli, and then migrate to the trachea and bronchi. The parasites stimulate the host response, producing pinkish-gray nodules which contain coiled worms. The nodules appear at about two months from infection that can cause chronic treacheobronghitis.

Not all infected dogs will have signs of lungworm infection. The most common clinical sign is loud, nonproductive cough, wheezing, and exercise intolerance. The most severe cases have been seen in dogs of 6-12 months old. Heavy infection can lead to loss of appetite and emaciation. A number of diagnostic tests are available to diagnose Oslerus osleri tracheobronchitis: fecal examination, chest radiographs, examination of coughed material (sputum), and tracheal washing will help to establish a definitive diagnosis. Infections with Oslerus osleri worms require a prolonged course of treatment with drugs which may have adverse affects. The prognosis for dogs treated with ivermectin is good; the drug appears to be successful in eliminating infection, but it cannot be administered to Collie and related breeds.3

Source: USDA


  1. Oslerus osleri tracheobronchitis: treatment with ivermectin in 4 dogs.
  2. Veterinary Parasitology. M. A. Taylor, R. L. Coop, R. L. Wall
  3. Small Animal Internal Medicine. Richard W. Nelson, C. Guillermo Couto