The trachea is the tube that carries air to the lungs. It consist of several semi-rigid cartilages in the form of a ‘’U’’. The dorsal portion consists of a membrane which closes the ‘’U’’ cartilage.
We do not yet know the cause of tracheal collapse. It most often occurs in middle or advanced aged dogs and affects mostly toy or miniature breeds. The cartilaginous rings lose their stiffness, which, over time, has the effect of stretching the dorsal membrane and finally inducing the collapse thereof. Collapses occur most often in the cervical or intra-thoracic region of the trachea.
The clinical sign most often reported by owners is the appearance of an occasional cough that increases in intensity and becomes chronic. It is often caused when pressure is applied to the trachea (dog pulls on leash, owner picks dog up under the thorax, etc..) The problem increases with excitement, physical exertion or anxiety. The mucous membranes (gums) of the animal may turn from a normal pink color to a bluish tint when the animal enters acute respiratory difficulty.
The diagnostic tests most often used include radiography and fluoroscopy. Radiography allows us to take static snapshots of the trachea during inspiration and expiration. Fluoroscopy, meanwhile, is an x-ray ‘’in motion’’ which reveals changes in the trachea in “real time”. Bronchoscopy (inserting a small camera into the trachea and bronchi) is a diagnostic test which allows us to assess the degree of the collapse of the trachea. We use this test less often because of the dangers presented when the animal is in the acute phase.
The treatment depends on the condition of the animal. In acute phase, the first step is to calm the animal, to reduce the anxiety which exacerbates the problem. Butorphenol and diazepam are the drugs most often used. If the animal is in severe respiratory difficulty and the mucous membranes are bluish, it will be necessary to put him in an oxygen cage. Corticosteroids will also be given to reduce the edema in the trachea. Finally, bronchodilators can be used to reduce spasms in small airways.
We use the same medication in chronic cases as we do with acute. The difference is in the frequency of administration and the dosage. We provide drugs only when necessary. Antitussive agents such as dextromethorphan, butorphanol and hydrocodone are used. Low-dose corticosteroids may also be prescribed.
Weight control is a key factor in treatment because obesity increases the symptoms of the collapse. We also recommend the use of a harness rather than a collar to reduce the pressure applied to the neck. Reducing exposure to products which may be irritating to the trachea, such as cigarette smoke and dust, allows for a better quality of life for the animal.
In extreme cases where even the medication is no longer sufficient to make the animal comfortable, the surgical fitting of an intra-tracheal prosthesis may be an option. It supports the cartilage and prevents them from collapsing.