Paralysis of the Larynx
A trip to the veterinary clinic is not always fun. It’s even less fun if you’re rushing your dog in as an emergency. One moment your dog is happy, healthy, and running around; the next moment it has collapsed on the ground and seems to be struggling for air. You rush to the veterinary clinic, the whole time thinking ‘What happened?’
Well, difficulty breathing can be due to a variety of problems like heart failure, pneumonia, or old age. In this case the diagnosis is laryngeal paralysis. Despite the fact that your dog suddenly had trouble breathing, laryngeal paralysis is actually a disease that progresses gradually. The initial signs are so mild that they may go unnoticed. These signs can be as subtle as a change in the way its bark sounds or it may cough a bit when eating.
What is laryngeal paralysis? It is paralysis of the larynx. The larynx is located at the back of the throat. It is a complex structure responsible for opening and closing the entrance to the trachea. The trachea is the hard, tube-shaped structure located in your neck that carries air to your lungs. The larynx acts like two doors that either shut or open at the same time. When your dog breathes, the larynx ‘doors’ are open and allow air to travel easily down the trachea and into the lungs. The two ‘doors’ of the larynx are closed when your dog is swallowing food or water. This is very important! With help from the epiglottis, the larynx helps prevent food from going into the trachea and lungs. In addition, the vocal cords are also located on the larynx which is why the larynx is sometimes referred to as the voice box. Vocal cords are responsible for your dog’s ‘voice’ (barking, whining, whimpering, etc.).
So we’ve come to the conclusion that the larynx is important to allow air into the trachea and to keep food out of the trachea. It is also where the vocal cords are located. Laryngeal paralysis is when the nerves that allow the larynx to open and close are damaged. Therefore, the larynx ‘doors’ do not open or close properly. In fact, the paralysed larynx doors do not move at all. Because the paralysed larynx does not move, the airway is blocked. Surprisingly, your dog can usually function fairly well at this point. You might notice that there is a change in bark (because the vocal cords are affected) or coughing when eating (because some food may be entering the trachea).
But what caused your dog to be in such sudden distress, and have so much trouble breathing? Usually there is a situation such as heat, exercise, or excitement that pushes the dog over the edge. This causes the dog to breathe faster and harder. As this happens, the paralysed larynx becomes pushed around by the fast moving air. It develops inflammation, which further narrows the entrance to the trachea. As this progresses, the opening to the trachea continually gets smaller until suddenly your dog is unable to get enough air to its lungs. Laryngeal paralysis can also be caused by direct injury (trauma) to the nerve, a disease that attacks nerves, or an inherited disease. However, there is usually no obvious cause of laryngeal paralysis. It can happen to any dog (or cat) at any age.
The treatment for laryngeal paralysis is always surgery. The goal is to open the entrance to the trachea enough to allow the passage of air, but at the same time to limit the chance that food can enter the trachea. There is a ‘tie-back’ surgery, when one ‘door’ of the larynx is permanently tied open. This is the most common surgery. There are also other methods, such actually cutting part of the larynx out completely. Dogs that have surgery have a good prognosis. However, there is a risk of post-operation complications. Aspiration pneumonia is one of those risks. This is when the dog breathes in food and it causes an often fatal pneumonia in the lungs. Dogs with other neurological signs also tend to have a poor prognosis, but most dogs resume a normal life and go on to live to an old age.
Laryngeal paralysis is a scary and sudden emergency. Some dogs have such severe problems breathing that they don’t even make it to the veterinary clinic alive. You can’t do anything to prevent laryngeal paralysis, but you can help your dog if it suddenly has trouble breathing. If your dog ever has trouble breathing, make sure to cool it off and calm it down immediately as you head to the veterinary clinic. Laryngeal paralysis is a dramatic problem, but it can have very successful treatment.