My dog was diagnosed with laryngeal paralysis | Dr. Justine Lee, DACVECC, DABT, Board-certified Veterinary Specialist

Posted by justinelee in Blog, Pet Health

Was your dog just diagnosed with laryngeal paralysis? Here’s what you need to know!

The larynx, otherwise known as the voice box, is made up of cartilage and works by allowing air to flow directly into the lungs. Muscles, nerves, and blood vessels surround the larynx. During breathing, the two halves of the cartilage should abduct (or pull open) to allow a large opening into the trachea to allow air to enter into the lungs. During swallowing, special tissue (e.g., the epiglottis) covers the larynx, which prevents food from entering the voice box (and hence, the lungs) while eating.

Medical problems with the larynx can occur, resulting in serious, potentially life-threatening airway problems in dogs and cats. Csauses for laryngeal problems include:

• Laryngeal paralysis
• Trauma
• Cancer
• Underlying endocrine medical causes

So, what exactly happens with laryngeal paralysis? Laryngeal defined as abnormal function of the voice box (the “larynx”). This may be due to a problem with the muscles attached to the larynx or due to the nerves that innervate the larynx. When laryngeal paralysis occurs, the two halves of the larynx may not be able to abduct (or pull back) themselves appropriately, resulting in a narrow diameter of the voice box. This can result in difficulty breathing (imagine breathing through a coffee stirrer versus a straw).

Laryngeal paralysis can be seen in either two forms: congenital (meaning an animal was born with it) or acquired (meaning the problem can develop over time). Unfortunately, it’s more prevalent in certain breeds, as it can be inherited or congenital (which means the dog was born with it). Breeds at risk for inherited, congenital laryngeal paralysis include:

• Siberian huskies
• Bouvier des Flandres
• Bull terries
• Mixed breeds with these at-risk breeds
• Dalmatians
• Rottweilers

Breeds at risk for acquired laryngeal paralysis include:

• Labrador retrievers
• Golden retrievers
• Irish setters
• Newfoundlands
• St. Bernards

Clinical signs of laryngeal paralysis include:

• A change in bark
• A high-pitched type of breathing (called “stridor”)• Exercise intolerance
• Coughing
• Heat intolerance
• Panting
• Agitation
• Difficulty breathing
• Blue gums (from lack of oxygen)
• Collapse
• Foaming at the mouth
• Hyperthermia
• Respiratory arrest (no longer breathing)
• Acute death

So how to we as veterinarians diagnose laryngeal paralysis? Typically, we need to diagnose it based on the history (e.g., pet owners noticing a change in bark), clinical signs consistent with laryngeal paralysis, physical examination findings, and an upper airway examination performed under sedation. Other tests that often need to be performed in patients with laryngeal paralysis include routine blood work (to look for the presence of underlying metabolic problems and to make sure sedation or anesthesia are safe), a complete blood count (to look for the presence of an underlying infection), chest x-rays (to look for the presence of aspiration pneumonia, a common complication of laryngeal paralysis), tests to evaluate appropriate oxygen levels within the body (e.g., arterial blood gas or pulse oximetry), and miscellaneous other tests (e.g., a thyroid test to rule out an underactive thyroid problem causing the problem). Other ancillary tests may include ultrasound (to look for evidence of cancer), fluoroscopy (a “moving” x-ray to look for a swallowing disorder), or even electromyography (to evaluate if the nerve is functioning).

More importantly, what can I do about it if my dog was just diagnosed with laryngeal paralysis? Treatment for laryngeal paralysis typically is either through medical or surgical management. Medical management includes:

• Weight loss (to add less strain on the lungs)
• Limited exercise
• Minimal stress (e.g., hot, humid days)
• Avoiding the use of collars or neck chains
• Limiting walks to cool weather
• Sedatives (e.g., acepromazine) to help relax the airway and prevent anxiety
• Steroids (to decrease airway inflammation)
• Antibiotics (to treat secondary aspiration pneumonia, if present)

If medical management fails to improve the breathing, surgery is recommended. Surgery involves either removing part of the cartilage that is blocking the airway (called a partial arytenoidectomy) or more commonly, performing an arytenoid lateralization. The second procedure, more commonly called a “tie back,” involves suturing (and literally “tying back”) part of the laryngeal cartilage to the side. This allows the airway to be open; however, the patient is more at risk for aspiration pneumonia due to the airway being permanently tied open. Patients undergoing a “tie back” can no longer swim, due to the increased risk of drowning also.

Unfortunately, there’s not much you can do to “prevent” it in your dog. In young patients presenting with laryngeal paralysis, a presumed inherited or congenital trait is suspected; neutering is recommended to prevent further transmission of the gene. In those with acquired disease, prevention of episodes of difficulty breathing is the goal. By attempting medical management (as mentioned above under “treatment”), some patients can live comfortably with the disease for years. However, pet owners need to be aware of the potentially life-threatening episodes that can occur, and should take all measures to prevent relapses. Also, make sure to keep your dog thin so the extra fat from obesity doesn’t contribute to more difficulty breathing.

When in doubt, consider making an appointment with a board-certified veterinary surgeon for further evaluation and treatment.

References:
1. Harpster NK. Laryngeal disease. In Blackwell’s Five-Minute Veterinary Consult: Canine & Feline. Eds. Tilley LP, Smith FWK. 2007, 4th ed. Blackwell Publishing, Ames, Iowa. pp 794-795.
2. MacPhail CM, Monnet E. outcome of and postoperative complications in dogs undergoing surgical treatment of laryngeal paralysis: 140 cases (1985-1998), J Am Vet Med Assoc 2001;218:1949-1956.