Chronic lower airway disease in the dog and cat

The most common form of lower airway disease (LAD) in dogs is chronic bronchitis, whereas in cats a syndrome resembling chronic bronchial asthma in humans is commonly reported. In most cases, the cause(s) of LAD remains unproven. The primary symptom of LAD in dogs and cats is chronic cough, although many cats are free of symptoms between episodes of acute, life-threatening bronchoconstriction. Diagnosis is based on a careful history, physical examination, and diagnostic tests designed to rule out other causes of cough and dyspnea such as pneumonia, heartworm infestation, and congestive heart failure. More sophisticated tests, such as bronchoscopy, flow volume loops, and radioisotope ventilation scans are available to define the extent of the disease process better. Glucocorticoids remain the mainstay of chronic therapy for most dogs and cats with LAD. Bronchodilators are indicated for most cats with symptoms of acute bronchoconstriction, whereas a smaller number of dogs may respond to bronchodilator administration and demonstrate an increase in exercise capacity and a decrease in cough frequency. LAD in dogs and cats is a progressive disorder, and prognosis is guarded. Nevertheless, with aggressive medical management many of these animals can live relatively symptom-free lives.