The larynx is the portion of the respiratory tract located between the pharynx and the trachea. The larynx contains the vocal cords, which form a "V" shape. The vocal cords are attached to the arytenoid cartilage, a pair of small cartilages located on either side of the trachea’s opening. When an animal takes a breath, air goes through the nose or mouth into the pharynx. As the air continues to the larynx, the arytenoid cartilages move away from the opening to the trachea, allowing air to pass.
Laryngeal Paralysis occurs when the arytenoids cartilages fail to abduct, or move away during inspiration. This creates an upper airway obstruction whenever the animal attempts to take a breath.
Laryngeal Paralysis usually affects both cartilages. It is most commonly seen in dogs and can occur at any age in any breed. Generally however, it is seen in large breed dogs, middle aged to elderly dogs, and dogs that are obese. Rarely, laryngeal paralysis affects cats. Horses can also be affected by laryngeal paralysis, a condition commonly called roaring because of the noise the horse makes during exercise.
Most of the time laryngeal paralysis is idiopathic, meaning there is no known cause. Laryngeal paralysis may be congenital in Bouvier de Flandres, Siberian Huskies, Dalmatians, Rottweilers, and Bull Terriers. Other less common causes include: trauma, certain neuromuscular disorders, tumors, or hypothyroidism.
Signs of laryngeal paralysis may range from mild to an emergency situation requiring immediate veterinary intervention. They include:
- Distinctive roaring/quacking noise during inspiration due to the airway obstruction
- Exercize intolerance
- Voice change or cough
- Blue mucus membranes (gums) from a lack of oxygen
- Difficulty breathing
- Gagging or retching
- Collapse
A definitive diagnosis of laryngeal paralysis requires laryngoscopy, which involves putting a tiny camera into the larynx to watch the arytenoid cartilages as the pet breathes. This requires sedation, and many times completely anesthetizing the pet to make the procedure less stressful.
Managing laryngeal paralysis involves treating the symptoms, and avoiding stress and excitement. In an emergency, the pet may require supplemental oxygen and sedation. If the cause of laryngeal paralysis is known, treating the underlying condition such as hypothyroidism, or obesity is also helpful. Medical management in cats is usually effective, but dogs and horses may require surgery.
The only successful treatment of laryngeal paralysis is surgical. There are many techniques including removal of the vocal cords, or partially removing the arytenoids cartilages. A unilateral or bi-lateral arytenoid lateralization, also called a tie-back surgery, is the recommended procedure. This technique has the lowest number of complications resulting from surgery, the shortest completing time, and the best survival rates.
A tie-back surgery is also considered the only permanent correction for laryngeal paralysis. This procedure involves suturing the arytenoid cartilages away from the opening of the trachea, preventing a collapse of the cartilage. A tie-back surgery may be preformed on one or both sides of the larynx.
As with any medical condition, it is important to talk to a veterinarian as soon as symptoms are noticed. It is better to diagnose laryngeal paralysis when the pet is experiencing mild symptoms then to wait until it is a medical emergency.
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