Dogs develop an asthma-like illness that is clinically referred to as allergic bronchitis. Generally, the condition is the result of an allergic reaction to something in the dog's environment that creates inflammation in the dog's upper airways. The allergen in allergic bronchitis in dogs is usually inhaled by the dog.
The symptoms of allergic bronchitis in dogs include obvious respiratory distress with difficulty breathing, dyspnea, wheezing and shortness of breath. The dog may also breathe with its mouth open and develop a dry, hacking cough. The dog's gums may turn blue, and the dog may lose interest in food, become lethargic and lose weight.