What is the larynx?
The larynx, or voice box, is made up of pieces of cartilage (a tough, flexible material) in the throat area. Its main job is to protect the windpipe and lungs by closing when a dog eats or drinks, so food and water don’t go into the lungs. The larynx opens when the dog breathes and closes when the dog swallows.
What is laryngeal paralysis?
Laryngeal paralysis is a condition in which the larynx can’t open all the way, causing it to partly block the trachea. The nerves that control the muscles around the larynx become weak (paretic) or stop working (paralyzed), so the muscles relax and cause the cartilage to collapse inward, over the trachea.
What causes laryngeal paralysis?
Laryngeal paralysis can occur for many reasons that can be separated into congenital (born with the condition) and acquired (the condition developed later in life). In congenital cases, the nerve that controls the larynx degenerates, along with the area of the brain that controls that nerve.
Recent research indicates that most dogs with acquired laryngeal paralysis have a neuromuscular (nerve and muscle) disease called geriatric onset laryngeal paralysis and polyneuropathy (GOLPP). Laryngeal paralysis is often one of the first signs of this disease.
In many cases of GOLPP, the leg muscles become weak over time, and the esophagus (the tube that carries food from the mouth to the stomach) becomes flaccid and distended (called megaesophagus), reducing the dog’s ability to move food and water to the stomach. The leg muscle weakness is generally slow to occur, and a dog may never develop these signs. The chance of developing megaesophagus, however, is about 21 times more likely in dogs who have GOLPP than in dogs who do not have it.
Other causes of acquired laryngeal paralysis include nerve damage or dysfunction caused by trauma to the throat or neck; tumors or space-occupying lesions; and endocrine (hormonal) diseases, such as hypothyroidism and Cushing's disease. Although hypothyroidism and Cushing’s disease are treatable, treatment generally does not improve the degree of laryngeal paralysis.
Do certain breeds develop laryngeal paralysis more commonly?
The breeds most affected by acquired laryngeal paralysis are Labrador retrievers, golden retrievers and St. Bernards. The congenital form is seen in Bouvier des Flandres, Siberian huskies, bull terriers, rottweilers and dalmatians, and clinical signs usually occur at an early age in these breeds.
What are the clinical signs of laryngeal paralysis?
The clinical signs of acquired laryngeal paralysis vary widely, potentially making it an underdiagnosed condition. Dogs with the congenital form usually show signs before they are one year old, but those with the acquired form are usually middle-aged or older.
One of the primary reasons the condition is underdiagnosed is because the initial signs often only involve a reduction in exercise (slowing down) commonly associated with age. Other signs include noisy breathing; gagging or coughing, often associated with eating or drinking; excessive panting; a change in the sound of the bark (dysphonia); or having trouble breathing. Unfortunately, all these signs are also associated with advanced age, cardiopulmonary disease, and bronchitis, especially if the dog is obese.
In sudden, severe cases, the dog may develop respiratory distress with bluish mucous membranes (cyanosis) of the mouth and may collapse. This distress is often caused by inflammation of the larynx triggered by excessive panting or increased breathing rate.
How is laryngeal paralysis diagnosed?
Laryngeal paralysis is diagnosed based on your dog’s medical history and clinical signs. As mentioned, coughing and shortness of breath are often the only early signs of the condition. Diagnostic tests that may be recommended include blood and urine tests and chest radiographs (X-rays) but, ultimately, an examination of the larynx with an endoscope or laryngoscope is needed to confirm the diagnosis.
How is laryngeal paralysis treated?
Mild cases of laryngeal paralysis may be managed with medications, such as anti-inflammatory drugs and sedatives. You can help your dog by avoiding hot environments and strenuous exercise. Do not use collars that will put pressure on your dog’s neck. Harnesses are recommended for affected dogs. In severe or congenital cases, surgery is often the best option.
What does the surgery involve?
There are several surgical techniques available. Surgery is based on the severity of your dog’s condition. A common surgical procedure involves tying the collapsed cartilage to the side of the larynx to prevent it from creating an obstruction to breathing. This is called arytenoid lateralization or a tie-back procedure.
Several other surgical techniques are also sometimes employed in treating this condition. Your veterinarian can discuss these options if they feel these treatments may be warranted. Surgery will often dramatically improve an affected dog's quality of life by improving airflow to the lungs, but it does not restore laryngeal function. Your veterinarian will discuss the anesthetic concerns and the surgical technique with you before surgery.
Patients with laryngeal paralysis are at slightly increased risk of anesthetic complications. After surgery, dogs may be at increased risk for aspiration pneumonia as their larynx remains more open when eating or drinking.
