Trachea is a tube or system of tubes that carries, moistens and warms the air while it passes into the lungs. The cartilage rings of the trachea are shaped like the letter C, lying on its back. A small membrane covers the top of the ring. In some dogs, the tracheal cartilage loses its rigidity, the trachea flattens and mild to severe obstruction of the airways develops. This is not a congenital disease. Tracheal collapse can occur in the neck region, within the chest, or in both locations.3 Many factors have been implicated, including genetic, nutritional, neurological, and muscular-skeletalal abnormalities. Many dogs have been shown to have a reduction in chondrocytes and lack of glycosaminoglycan, chondroitin sulfate and calcium in tracheal cartilage. This leads to weakening of the cartilage and flattening of the tracheal rings. In many dogs with this disorder the principal bronchi are also collapsed. When bronchial collapse is also found in conjunction with tracheal collapse, this is called tracheobronchomalacia.1,2 The Yorkshire Terrier, Pomeranian, Toy Poodle, Maltese, Chihuahua and other toy and miniature dog breeds are at greater risk than larger breeds. Early diagnosis and treatment usually give the dog a better quality life. Response to medical therapy is usually temporary and the disease typically progresses.
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The disorder reveals itself through many signs, but some dogs may have no signs at all. In some cases, dogs will have chronic "goose-honk" cough, noisy breathing and gagging, wheezing, hacking, and exercise intolerance. In severe tracheal collapse, there may be a bluish discoloration to the gums and skin due to lack of oxygen, and the dog may faint. These signs are usually more severe in obese animals. The disease is diagnosed by using radiographs and feeling the neck area. Although chest X-rays demonstrate tracheal collapse only in 60% of affected dogs, they help rule out heart and lung diseases as a cause of the signs.3 Treatment aims at reducing coughing and chronic airway injury; keeping the dog away from irritants, such as cigarette smoke, exposure to extreme cold, heat, and humidity; using a harness instead of a collar; reducing food intake (if the dog is overweight), and anti-inflammatory therapy. In severe cases, emergency surgery is performed and prostheses are applied. Surgery relieves many of the signs of tracheal obstruction, but does not cure the disease. The success rate for prosthetic rings is reported to be 75% to 85%.2 Following surgery, most dogs are more active, breathe easier, cough less, and require less medical treatment for respiratory diseases.
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