A weakening in the cartilage rings within a dog's trachea causes the trachea itself to lose its structure and collapse, explains PetEducation.com. The cause of this weakening is unknown, although a congenital abnormality causing the cartilage rings to form in less circular manner might be a factor, according to WebMD.
The most characteristic symptom of a collapsing trachea is a cough that resembles a honk, claims WebMD. Other symptoms of a tracheal collapse include difficulty breathing and a bluish color in the gums. Signs of tracheal collapse typically manifest around the age of six or seven. Yorkshire terriers are the most commonly affected breed of dog. Surgical procedures to alleviate the problems created by a tracheal collapse by reopening the airway are available to dogs who do not experience an improvement with typical treatments such as cough suppressants.