The trachea, which carries air from the throat to the lungs and back again, is a soft tube held in a semiround shape by a series of C-shaped rings of cartilage. The ends of the cartilage are connected by a flexible membrane. When the cartilage rings are malformed, or the cartilage degenerates over time, the trachea flattens or collapses.
No one yet understands exactly how or why this happens. Because it occurs most often in certain breeds, including Yorkshire terriers, a genetic component is suspected. An abnormality, probably inherited, in the chemical composition of the rings causes them to soften and lose their rigid shape.
The sign most often noted by owners is a chronic cough. It occurs because the flexible membrane, no longer held taut, droops and tickles the lining of the trachea. Coughing happens more during the day than at night, and is often described as a dry, honking cough. Pressure from a collar, excitement, and exercise can all initiate coughing. Symptoms generally worsen in hot, humid weather, when the dog needs to pant. Dogs suffering from collapsing trachea may be unable to exercise without coughing. Eating and drinking can also bring on coughing.
Dogs with a collapsing trachea should not wear a collar or even a harness that could create pressure on the trachea. If a harness is your chosen alternative, be sure it doesn't ride up the chest. You could also use a head halter to avoid pressure on the throat or chest.
A breed subject to the problem and a history of coughing are enough to raise strong suspicion of the existence of the condition. Lightly pressing on the trachea during a physical exam can often induce the cough, but definitive diagnosis requires testing.
X-rays (radiographs) of the chest can show the shape of the trachea. However, this is a tricky proposition because a collapsing trachea changes its shape between inhalation and exhalation. The technician has to manage to take radiographs during both phases of respiration, which is not an easy accomplishment. Because coughing can also be an indication of heart disease, your veterinarian might also recommend a chest x-ray to be able to check the heart.
Fluoroscopy is also an x-ray procedure, but one that provides an ongoing real-time look at the trachea throughout respiration. Endoscopy (a procedure also conducted on humans) offers an entirely different option, sending a flexible tube down into the trachea for an interior look at the structure.
Reverse sneezing is another cause of coughing common in toy breeds. It's caused by a temporary spasm in the back of the throat and does not require veterinary intervention. The cough sounds like someone with badly stuffed sinuses trying to inhale hard. Gently rubbing the throat can soothe the coughing, but it should cease on its own in under a minute.
Nonsurgical treatment involves taking care of any concurrent conditions that worsen the problem, and avoiding environmental triggers. If the dog is overweight, weight loss will likely be the first recommendation. Overweight dogs in general have a harder time breathing, and they pant under less exertion and at lower temperatures. You should also avoid exertion hard enough to force the dog to pant, and do your best to keep the dog from becoming overexcited. Also, keep the dog away from dry, dusty locales; don't smoke around the dog; and use a cool-water humidifier in the house to keep air moist.
Medicines might be given to help with the problem. The same bronchodilators used for humans are used for dogs. Time-release formulations are used for dogs so they don't have to be given as often. Anti-inflammatory medications — corticosteroids — may also be used to ease the swelling of the trachea. Because of side effects, they should be given short-term only. Finally, cough suppressants might be recommended.
A veterinary survey showed that over 70 percent of dogs diagnosed with collapsing trachea responded to management of concurrent conditions and medication. Roughly 15 percent were found to be candidates for surgery. The chance for improvement after surgery is good if the collapsing portion of the trachea lies in the throat rather than in the chest. Dogs under six years of age fare better than older individuals. The surgery generally involves placing a prosthesis around the trachea, and it must be performed by a specialist. A new surgery option uses a stainless steel self-expanding prosthesis, placed in the trachea as a stent. While this is still a fairly rare choice, its results have been excellent.