Infection of the respiratory tree is in some ways similar to infection of the stomach and intestines by gastrointestinal parasites like roundworms or hookworms, although it is less common. The lungworm injures the airways or lung tissue by inciting an inflammatory reaction. The parasites live and reproduce in the respiratory tissues.

Dogs acquire lungworms by eating one of the "hosts" that serve the lungworm during part of its life cycle. The life cycle of the different parasites can be complicated, involving both intermediate hosts and transport hosts.

The summary of specific lugworms parasites, the species each affects, the lifecycle of each and the geographical distribution of each is as follows:

Paragonimus kellicotti affects dogs and during its lifecycle, the intermediate hosts are the crayfish and snail. The transport host is the raccoon. The geographical distribution is North America.

Capillaria aerophilia has a direct lifecycle. Its geographical distribution is North America.

Osleri and Filaroides ssp. both affect dogs and each has a direct lifecycle. The geographical location of each is worldwide.

The major symptom of lungworms is coughing. Of course, there are numerous causes of cough or other signs similar to lungworms. Some common examples include:

Infectious tracheobronchitis

Tracheal collapse

Airway obstruction (foreign body, tumor)

Bronchitis

Respiratory infections

Heartworm disease

Heart disease

Allergic lung diseases

Pneumonia

Pulmonary granulomatosis (type of inflammation)

Pulmonary neoplasia (tumors)

Hepatopulmonary migration of enteric worms (intestinal worms, such as roundworms, spend time migrating through the lungs and liver in younger dogs)