Overview of Laryngeal Paresis and Paralysis in Dogs
Laryngeal paralysis, commonly abbreviated as LP, is a dysfunction of the larynx, or voice box that is a common problem in dogs. The larynx is located at the entrance to the trachea or windpipe and is covered by a movable, valve-like structure or flap called the epiglottis, which covers the windpipe when we swallow to prevent food from entering the trachea. The larynx itself also closes to prevent aspiration of food and water and acts to control airflow into the windpipe.
Laryngeal paresis (weakness) is caused by malfunction either of the muscles that move the two halves of the larynx into an open position, the nerves that control those muscles, or both. In laryngeal paresis/paralysis the larynx fails to open properly during inhaling, and this leads to airway obstruction.
Acquired idiopathic (unknown cause) laryngeal paralysis, the most common form of the disorder, occurs more commonly in middle aged or older, large breed dogs, such as Labrador retrievers, golden retrievers, and St. Bernards. Less commonly, the disease can occur secondary to injury to the larynx or laryngeal nerves, neuromuscular disease, or it may be congenital in some breeds.
If the disease is allowed to progress over time, the quality of the pet’s life decreases because of the inability to inhale sufficient oxygen to permit even the simplest of activities. Fainting, severe respiratory distress, or death may result.
What to Watch For
Signs of laryngeal paresis and paralysis in dogs may include:
Gagging or coughing during eating or drinking
Respiratory stridor or noisy breathing
Difficulty breathing (dyspnea)
Cyanosis (blue color due to lack of oxygen)
Diagnosis of Laryngeal Paresis and Paralysis in Dogs
Diagnostic tests are needed to recognize laryngeal paralysis and differentiate it from other causes of respiratory difficulty. These may include:
Physical examination, including auscultation of the chest with a stethoscope
Thoracic radiographs to rule out primary heart or lung disease
Thyroid gland function tests to rule out hypothyroidism (low levels of thyroid hormone).
Direct examination of the larynx. This is the definitive diagnosis and is made while the dog is breathing and under a light plane of general anesthesia.
Treatment of Laryngeal Paresis and Paralysis in Dogs
Treatment of mild cases
Mild cases may respond well to medical management which includes maintaining a healthy body weight and sedentary lifestyle, and avoiding stressful situations (such as exercise during hot, humid weather).
Occasionally oral sedatives or tranquilizers may be administered.
Avoid using a neck collar – use a harness instead.
Treatment in moderate to severe cases
Dogs that have severe difficulty breathing are considered to be in a cyanotic crisis and must be stabilized initially with oxygen. Initial treatment also includes body cooling if the temperature is abnormally high, corticosteroids to reduce laryngeal swelling, and in very severe cases with a temporary tracheostomy, which is a quick surgical opening into the trachea to allow breathing.
Once stabilized, definitive surgical treatment is usually recommended. Procedures that may be performed include either removal of the part of the larynx that is obstructing the airway (a partial arytenoidectomy) or suturing part of the larynx in an open position out of the flow of the airway (arytenoid lateralization or”tie back”).
Home Care and Prevention
Take your dog to the veterinarian as soon as the first signs of respiratory difficulty arise. If your veterinarian prescribes medical management, keep your dog from overly stressful situations, avoid excessively warm days outside, avoid letting your dog become overweight, and always use a harness-type leash instead of a neck collar. Watch your dog to make sure his condition does not worsen.
If surgical management is prescribed, watch for potential complications after surgery such as:
Drainage, swelling, or redness of the incision
Recurrence of respiratory difficulty
Gagging or coughing during eating or drinking
Because most cases of laryngeal paralysis are acquired later in life and have no known cause (idiopathic) prevention is not possible.
In-depth Information on Laryngeal Paresis and Paralysis in Dogs
Laryngeal disease is just one of many causes of difficult breathing in dogs. Other causes of respiratory distress include:
Upper respiratory neoplasia. Tumors of the nasal cavity, pharynx, larynx, or trachea can cause respiratory difficulty as the air passage is partially obstructed by the mass.
Laryngeal collapse. A very severe, end-stage condition of the larynx caused by chronic increased inspiratory effort and subsequent weakening of the laryngeal cartilages that would normally hold the walls of the larynx out of the airway.
Cardiac disease. Ineffective pumping of oxygenated blood to the body because of a faulty heart can cause dyspnea and weakness.
Pulmonary disease. Ineffective oxygenation of the blood caused by lung disease can cause shortness of breath and dyspnea.
Tracheal collapse. Usually found in small dog breeds, tracheal collapse is caused by weakness of the cartilage rings that normally hold the trachea open during breathing leading to a severe “honking” cough and dyspnea.
Brachycephalic syndrome. A group of conditions that cause resistance to airflow through the upper respiratory tract in short-nosed dog breeds.
Hypothyroidism. An endocrine disorder in which insufficient thyroid hormone is secreted by the thyroid gland. It can be a cause of neuromuscular disorders and is sometimes found concurrently in dogs with laryngeal paralysis.