INFORMATION IN-DEPTH

Tracheal collapse is a common cause of airway obstruction in dogs. The condition was first described in dogs in 1941. The trachea (windpipe) is normally a rigid circular tube. Typically, if the trachea collapses, it is compressed from top to bottom, as opposed to side-to-side. The section that collapses is usually the part of the trachea that enters the chest, but it can occur anywhere, from the throat all the way down to the first part of the lungs

Tracheal collapse is mainly a disease of toy-breed dogs of either sex. Yorkshire terriers are most commonly affected, but Pomeranians, Chihuahuas, poodles, Maltese and pugs are also predisposed. Any age dog can be affected, but the average age at which clinical signs first occur is usually six or seven years.

Dogs are brought to the veterinarian with a history of coughing for several weeks or months, although, less commonly, it may present as a sudden episode. Other possible presenting signs are intolerance to exercise, labored breathing and cyanosis (bluish tinge to the gums). Excitement, eating, drinking, irritants like smoke or dust, obesity, excitement and hot or humid weather may provoke a coughing spasm.

The cause of the collapse is unknown, but there are probably several factors at play. Abnormal synthesis of the components that make up the cartilage found in the trachea is believed to be the cause of tracheal weakness. The weakened trachea flattens from top to bottom, obstructing the flow of air in and out of the lungs.

There are other possible causes of tracheal collapse, such as congenital defects, chronic airway disease, trauma and tumors that compress the trachea from the outside. There are other conditions that can cause coughing, and this can exacerbate the collapse of the trachea. For example:

• Extra-long Soft Palate
• Obesity
• Chronic Bronchitis
• Pneumonia
• Congestive Heart Failure
• Respiratory irritants such as smoke or excessive dust
• Allergic Bronchitis

Once collapse has occurred, coughing will perpetuate further coughing by causing irritation and inflammation of the trachea. The irritated trachea will produce mucus and other secretions that further obstruct the airway. Medical treatment is undertaken to try to break the cycle of coughing, inflammation and excessive mucus production. If medical therapy fails, surgical therapy may be attempted.

VETERINARY CARE IN-DEPTH

Diagnosis

• Palpation of the trachea. On physical examination, if gentle pressure on the trachea elicits the characteristic "goose honk" cough, this is supportive of a diagnosis of collapsing trachea.
• X-rays. X-rays taken during both inhalation and exhalation are often needed to demonstrate tracheal collapse as well as to identify any concurrent heart or lung problems. During inspiration, the trachea in the neck tends to collapse. During expiration, a portion of the trachea that is found in the chest tends to collapse.
• Fluoroscopy. X-rays are not always diagnostic. Fluoroscopy is a continuous x-ray that allows the observation of the trachea while the dog is actually breathing or coughing. This procedure is typically available only at universities or referral centers.
• Tracheobronchoscopy. If surgery is being considered, or if X-rays or fluoroscopy still haven't yielded a definite diagnosis, tracheobronchoscopy can be used to confirm the diagnosis. This procedure involves the insertion of a bronchoscope into the trachea. The bronchoscope has a light and a camera on the end of it. The entire trachea may then be visualized, from the inside. This procedure may need to be performed at a university or referral center.

Treatment

Treatment for tracheal collapse will not cure the condition. Treatment consists of medical management and/or surgical intervention. Approximately 71 percent of dogs undergoing medical management of tracheal collapse show long-term resolution of clinical signs. As a result, medical management should be attempted first.

Medical Management

• If tracheal collapse presents as a respiratory emergency, patients must be stabilized immediately. Dogs are put into an oxygen cage. Administration of a rapidly acting steroid to reduce inflammation of the trachea and larynx is often necessary. Cough suppression and sedation may be necessary to stabilize the dog.
• • Chronic management of a collapsing trachea is based on the severity of clinical signs. Mild cases may need only a cough suppressant. More severe cases may require a combination of cough suppressants, airway dilators, steroids, and/or antibiotics Weight loss helps decrease the required respiratory effort in overweight dogs with collapsing tracheas.
• If two weeks of medical treatment hasn't helped, or if clinical signs are very severe, surgery may be attempted. Many procedures have been tried, but the one that is currently in favor is the application of prosthetic polypropylene rings around the trachea. The overall success rate in significantly reducing clinical signs is 75 to 85 percent. Prognosis is better for dogs younger than six years of age. This procedure should be done by an experienced surgeon.

FOLLOW-UP

Optimal treatment for your pet requires a combination of home and professional veterinary care. Follow-up can be critical, especially if your pet does not rapidly improve.
Administer all prescribed medication(s) as directed. Alert your veterinarian if you are experiencing problems treating your pet. Maintain the dog's weight at a proper level. Avoid obesity, which can exacerbate clinical signs. Use a harness instead of a collar, to avoid putting pressure on the trachea. Isolate the dog from potential respiratory irritants such as cigarette smoke, noxious fumes or excessive dust.