Chronic bronchitis is a disease affecting the smaller airways that branch out from the trachea. These branches called bronchi and bronchioles allow the transport of air into and out of the alveoli where oxygen exchange occurs.

Inflammation in the airways results in excessive secretions that plug the airways. The end result is an impaired ability to bring oxygen into the alveoli for delivery to the rest of the body. Chronic bronchitis is associated with inflammation and swelling of the walls of the bronchi. This results in narrowing of the airways and obstruction of airways by plugs of mucus or other secretions. Chronic bronchitis occurs when bronchitis last 2-3 months and is associated with irreversible changes in the airways.

Causes include bacterial infections, allergies, parasites or chronic inhalation of airway irritants. Underlying cause of chronic bronchitis is usually not determined.

Clinical signs consist of daily coughing, difficulty breathing or wheezing for 2-3 months or longer. Episodes of coughing can mimic vomiting because some dogs retch after coughing. In severe cases there is marked exercise intolerance.

Diagnosis can be made by chest radiographs. Radiographic changes of airway disease along with a history of middle to older aged dog with cough for 2-3 month duration may be sufficient to establish clinical diagnosis of chronic bronchitis. Bronchoalveolar lavaged may be recommended for some dogs. This procedure allows collection of fluid and cells from the lungs.

Treatment includes first identifying and treating any underlying disease. Changes in the environment should be implemented since these dogs have sensitive airways. Exposure to smoke, carpet fresheners, insecticides, hairspray, perfumes and cleaning products should be eliminated or minimized.
Two classes of medications most effective at treating chronic bronchitis are bronchodilators and corticosteroids. Bronchodilators help to open the airways by relaxing the muscles around the airway walls. Corticosteroids are anti-inflammatory drugs that decrease the inflammation and swelling of the airway walls. Cough suppressants can be prescribed in cases where cough is persistent.

Prognosis is variable. In most cases permanent damage to the airways has occurred and disease cannot be cured, but controlled with proper medical management. Cough is usually not completely eliminated, but reduced. Keeping dogs at an ideal body weight also makes breathing easier on the patient.