Tracheal collapse is a narrowing of the inner diameter of the trachea, that fluctuates with the stage of the respiratory cycle. The rings of the trachea (made of cartilage) lose their ability to maintain their shape, and collapse when the dog breathes, causing a harsh cough. Most often this disorder is seen in middle-aged toy and miniature breeds. Chronic respiratory infection, obesity, and heart disease can all contribute to the development of the condition, but it appears that there is also a congenital deficiency (ie. a dog is born with it) in the make-up of the trachea itself.
How tracheal collapse is inherited is unknown. This disorder occurs almost exclusively in toy and miniature breeds.
Ideally, affected dogs should not be used for breeding. This is difficult in practice however, because many affected dogs do not develop signs of this condition until middle age, when they have already been bred. It is preferable not to use lines of dogs for breeding in which collapsing trachea is a problem.
