Tracheal Collapse

Tracheal collapse is a chronic, progressive disease of the trachea, or windpipe. The trachea is a flexible tube and, similar to a vacuum cleaner hose, it has small rings of cartilage that help keep the airway open when the dog is breathing, moving, or coughing. The rings of cartilage are C-shaped, with the open part of the C facing upward. Between the two ends of the C is a long band of tissue- the dorsal membrane- that runs the length of the airway. In some dogs, the C-shaped cartilage becomes weak and begins to flatten out. Initially it becomes U shaped but, as the dorsal membrane stretches, the cartilage rings get flatter and flatter until the trachea collapses (Figure 1). The collapse can extend all the way into the bronchi- the tubes that feed air into the lungs, resulting in severe airway compromise in the animal. Figure 1. Diagram of tracheal collapse. Tracheal collapse is graded mild (Grade 1 = 25% collapse) to severe (Grade 4 =100% collapse). The trachea in dogs most often collapses at the thoracic inlet (green arrows) where the trachea bends to enter the chest. Initially dogs may present with a harsh dry cough that sounds like a goose honking. Coughing may occur when the dog is picked up or if someone pulls on its collar, since either may put pressure on the airway. As the disease progresses, the dogs may develop exercise intolerance or even turn blue with excitement. The strain of breathing may cause secondary heart disease. Some dogs may also have laryngeal paralysis along with tracheal collapse; the cartilages at the entrance to the windpipe will not open properly and the dogs will develop a wheezy noise when they breathe inward. Small breed dogs are most commonly affected with the disease, particularly Yorkshire terriers, Pomeranians, poodles, and Chihuahuas. Affected dogs are often middle aged or older, though it can be seen in some young dogs as well. Dogs that are overweight or that live in household with smokers may be more at risk or at least more likely to show clinical signs. Medical management includes weight loss, cough suppressants, antispasmodics or bronchodilators to reduce airway spasms, and sedation to reduce coughing and anxiety. Some dogs may require heavy doses of sedation to break the coughing cycle, since coughing will irritate the airway and lead to more coughing. Additionally dogs should be kept away from smoke and other environmental pollution (coughing may be even stimulated by smoke or other irritants brought in on clothing and hair). Dogs with infections are treated with antibiotics. Medical management may work for up to 70% of dogs, particularly those that have mild collapse. Some animals do not respond to medical management, however, and require surgical or interventional treatment. Collapse of the trachea in the neck or thoracic inlet- the front part of the chest where the trachea bends- is treated by surgical placement of plastic rings (Figure 6, 7) or spirals around the outside of the trachea. If the collapse is deep within the chest, it can sometimes be corrected by placing a stent- a spring like device- inside of the airway to hold the trachea open (Figure 8). Most dogs that receive stents will require ring placement in the neck or thoracic inlet region as well. Medical management is continued after the surgery, and most dogs are placed on a course of steroids to reduce swelling and irritation from the ring or stent placement. Owners must continue to keep their dogs thin and avoid exposing them to smoke or other airway pollutants. Also, they should use a harness that is specially made to fit low on the chest so that no pressure is put on the neck area when the dog is being walked. In winter months, a humidifier may help relieve irritation from dry, heated air. At this time there is no known prevention for tracheal collapse, although reducing weight or exposure to airway irritants such as smoke may help. About 70% of dogs that are treated with medical management alone will show some improvement. About 20% of dogs that undergo tracheal ring placement will require a tracheostomy- a temporary or permanent breathing hole in the neck. About 75% of dogs improve after surgical placement of rings. Dogs that are older than 6 years of age or that have laryngeal or bronchial disease have more complications and a poorer long-term outcome. Of dogs that receive stents, 95% are immediately improved and 90% are markedly improved at the time of recheck. Control of coughing is important for a good outcome, and dogs with bronchial collapse (and therefore continued coughing) are much more likely to have problems after stent or ring placement. This information on Tracheal Collapse and much more can be found on the American College of Veterinary Surgery's website! acvs.org