Tracheal Collapse, Canine - contd.
The trachea is the upper airway tube that carries inspired and expired air between the nose and mouth and the airways and lungs. The trachea is formed by separate incomplete cartilaginous rings, which are connected by fibrous connective tissue and muscle. In normal dogs, the trachea remains open or patent at all times. If the tracheal rings become weak for any reason, the normal action of breathing can result in the collapse of the trachea in that area.
If the tracheal rings are abnormal in the neck of the dog, the collapse usually occurs when the animal inhales. Conversely, the trachea tends to collapse during expiration when the abnormal tracheal rings are inside the dog's chest cavity. This distinction is the result of varying pressure gradients created during the different stages of respiration. Once the trachea has collapsed, the airway is obstructed and air is no longer able to move.
Dogs with tracheal collapse may have any of various symptoms depending on the severity of the condition. Some dogs may make an almost musical sound when breathing, and gag or cough to try to reopen the airway. Some may faint if severely affected. Treatments range from medications to help control excessive coughing to surgical stabilization of the tracheal rings. Some preventive measures may decrease the incidence of tracheal episodes.
