Laryngeal Paresis and Paralysis

Laryngeal Paresis and Paralysis

By: Dr. David Diamond

Section: Overview

Laryngeal paralysis is a dysfunction of the larynx, or voicebox. 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

  • Voice change
  • Gagging or coughing during eating or drinking
  • Exercise intolerance
  • Respiratory stridor or noisy breathing
  • Difficulty breathing (dyspnea)
  • Cyanosis (blue color due to lack of oxygen)
  • Fainting (syncope)

    Diagnosis

    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 in 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.

     
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