Collapsing tracheas occur most often in small dogs. These dogs usually have a chronic “honking” cough. The trachea, or windpipe, is a tube that carries air from the mouth to the lungs. It is composed of rings that normally have a circular shape. A collapsing trachea is a flattening or narrowing of these rings as they pass through the throat or chest. Obesity and enlargements of the heart or liver complicate the disorder.

While the cause of collapsing trachea is unknown, congenital forms have been recognized–a finding that suggests it may be hereditary in some dogs.