Do you have a small dog with a chronic cough? It might be due to a collapsing trachea. The trachea, also known as the windpipe, is the tube that allows air from the nose, mouth, and throat to travel to the lungs. It is made of a string of “C” shaped cartilage rings connected by muscle. The opening in the “C” faces the spine and is covered by another muscle called the tracheal membrane. In dogs with a collapsing trachea, there is a defect in the development of the cartilage ring making it weak. When the rings are weak, the tracheal membrane does not stay stretched tight during breathing but is droopy and will suck down into the “C” obstructing breathing and stimulating a cough when it touches the lining of the trachea. This repetitive contact with the tracheal lining leads to inflammation and mucous secretion which then increases coughing. The faster a dog breathes the more this happens so a cough is often heard when these dogs get really excited. This can be with exercise or the excitement of a visitor arriving. The trachea has two parts – the first section is in the neck and is known as the extrathoracic trachea and the second section is in the chest and is known as the intrathoracic trachea. Either or both parts can be affected. The most common place it happens is at the point where the trachea enters the chest. The dog may panic when it feels this obstruction to its breathing which makes it pant and breath even faster leading to a vicious cycle of pant- cough – panic – pant faster – cough more. This condition is thought to be hereditary and is seen more commonly in toy breed dogs – especially Poodles, Yorkies, and Pomeranians.
So how do you know if your dog’s cough is due to a collapsing trachea? Some of the classic symptoms are a “goose honk” like cough with excitement, tendency to cough when picked up, tendency to cough when their collar is pulled, exercise intolerance, gums turning blue when they cough, and wheezes when they breathe in. Sometimes this flattening of the trachea can be caught on chest xrays but not always. To diagnose it definitively sometimes requires placing a small endoscope into the windpipe of the dog while it is under anesthesia to witness the collapse or using fluoroscopy, which is like a moving xray, to catch this occurring.
I have noted that this is believed to be hereditary but there are some factors that can make it worse or take a dog with only a minor problem and turn it into a major one. One of the big factors which can make this condition worse is obesity. In addition, respiratory infections, air irritants like smoke and dust, heart enlargement, and intubation for anesthesia can all exacerbate this condition.
Most dogs (70%) can be managed long term with medications and lifestyle changes. All of the above exacerbating conditions must be controlled or corrected – especially keeping these dogs at a healthy weight. These dogs may periodically need antibiotics because they don’t clear their lower airways as well as dogs with normal tracheas. They often need chronic cough suppressants and intermittent steroids to control the inflammation caused by repetitive coughing. There is debate concerning the use of medications that dilate the airways because these often don’t work on the trachea, only on smaller airways. Air irritants should be avoided and harnesses used instead of collars. It can also be beneficial to use humidifiers in the winter to soothe their airways. In the case of a crisis when they cannot stop coughing or get enough air moving, they made need sedation to alleviate the panic that often escalates the problem.
If medical management fails, there are two types of surgery that may at least lessen the severity of the condition even if they do not eliminate the cough altogether. In the first type of surgery, metal rings are attached to the outside of the windpipe to hold it open. About 75% of the dogs that can’t be managed medically will respond to this surgery. The second type of surgery (which is the one more commonly used now) involves placing a mesh tube as a stent INSIDE the trachea to hold it open. About 90% of dogs will improve with this surgery. There can be many complications associated with these surgeries so they are only considered for dogs that are severely affected and don’t respond to medical management. Even with surgery, dogs will likely still need some meds to control coughing. Tracheal collapse is a chronic, progressive, and irreversible disease so management rather than cure is the objective.
Jul 25 2017