Laryngeal Paralysis in Dogs
The larynx is a little structure made of cartilage that sits in the throat and opens into the trachea, or windpipe. When the animal breathes in, the cartilages that make up the larynx are pulled apart to allow air to flow through. When the animal swallows, the larynx closes up to force food into the esophagus rather than into the airways. Laryngeal Paralysis in dogs is a condition whereby due to dysfunction of the nerve or muscles that control the larynx, the laryngeal cartilages are not pulled apart when the animal breathes.
When the cartilages remain in the airway, this causes an upper airway obstruction and interferes with the flow of air into the trachea. Imagine drinking water through a straw……then imagine if someone squeezes the straw to make it really narrow and how much harder it would be to drink water through that. This is similar to the feeling that dogs with paralysis of the larynx have. The result is that dogs may suddenly collapse or have trouble breathing. The anxiety that comes with this makes the whole situation worse. The gums may become pale or blue-ish and the breathing will be very loud and raspy. In some cases there is a more gradual onset, with excessive panting, noisy breathing and a reduced tolerance to heat or exercise. Coughing may also be seen.
Laryngeal Paralysis occurs mainly in large breed dogs. It can happen due to some sort of structural problem, such as a tumour, that is interfering with the path of the nerve controlling the larynx. It can also occur secondary to conditions that cause nerve or muscle weakness, such as hypothyroidism or myasthenia gravis. In rare cases, the pup can be born with laryngeal paralysis. In the majority of cases however, it occurs in middle aged to older dogs for reasons that we are yet to identify. Breeds that seem to be more prone to it are Setters, Labradors and other sporting breeds.
Diagnosis involves a general anaesthetic and examination of the larynx. Treatment is surgical, and involves the surgeon tying back one side of the larynx to enable it to stay open while the dog breathes. There will also need to be lifestyle changes, such as minimising heat or stress and feeding from a height, following the surgery.
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