Laryngeal Paralysis or “Lar Par” is the inability of the larynx or “voice box” to open when a dog breaths in and out and close when they are eat or drink. The larynx plays an important role in breathing by allowing air to enter the trachea and the lungs, and prevents food and water from “going down the wrong tube.”

The larynx is made up of the vocal cords, the laryngeal muscles and the arytenoid cartilages. The recurrent laryngeal nerve controls the laryngeal muscles (the muscles of the larynx) pulling back the arytenoid cartilages (think of these like curtains in the airway that open and close) during breathing. When the nerves to the muscles stop functioning properly, they stop telling the muscles to contract and the cartilages (the airway curtains) don’t get out of the way during breathing, limiting the ability of air to flow in and out of the lungs.

Larynx

Normal Airway

Normal larynx with functioning muscles and arytenoid cartilages.

Laryngeal Paralysis

Obstructed airway

Arytenoid cartilages are obstructing the area due to inability of the laryngeal muscles to contract.

What causes a Laryngeal Paralysis?

There are several causes of laryngeal paralysis. Some are curable and some are only manageable by medication and/or surgery.

  • Congenital – a dog is born with laryngeal paralysis. This type is rare and most dogs with congenital lar par do not live long. Surgical treatment is not effective.
  • Hereditary – a dog is genetically predisposed to laryngeal paralysis. This type of lar par is seen in Bouvier de Flanders and Bull Terriers among other breeds. Surgery can help improve quality of life.
  • Trauma – such as from a neck wound (e.g. bite) or other surgical procedure in the neck. Depending on the severity of the injury, this type of laryngeal paralysis can be cured.
  • Cancer for example cancer of the throat or neck can spread to the area or a tumor can put pressure on the nerves. The success of treatment is dependent on restoring function to the nerves that control the laryngeal muscles.
  • Nerve Degeneration – This is likely the most common cause of laryngeal paralysis and is known as geriatric onset laryngeal paralysis and polyneuropathy (GOLPP) or late onset laryngeal paralysis. It is managed through medication, lifestyle changes and often surgery. It also involves degeneration of the nerves elsewhere in the body, hence polyneuropathy.
What are the signs and symptoms of a Lar Par?
  • Loud breathing, which can sometimes sound like roaring. Worse when the dog is panting.
  • Distressed breathing when hot, excited or stressed
  • Change in bark – deeper, hoarse or raspy sounding
  • Exercise intolerance
  • Coughing
  • Throat clearing (like when you have a tickle in your throat)
  • Inspiratory stridor is hallmark of laryngeal paralysis and is the term for a noisy inhalation
How is laryngeal paralysis diagnosed?

There are two types of diagnoses for laryngeal paralysis:

Presumptive diagnosisbased on clinical history and ruling out other causes. This often may include a physical exam, blood work and chest x-ray.

Confirmed diagnosis – laryngeal paralysis can only be confirmed by examining the larynx directly. This involves light sedation of the dog and using a laryngoscope to view the function of the larynx, specifically the arytenoid cartilages.

What is the treatment for laryngeal paralysis?

Mild cases of laryngeal paralysis can be managed with medication to reduce inflammation in the airway and to keep a dog calm (i.e sedative such as trazadone). Antidepressant medications have been suggested to help but studies have not backed up this claim.

Keeping dogs calm, managing activity and avoiding overheating are also keep to management as this will limit heavy breathing. Switching from a collar to a harness is necessary to maximize air flow through the larynx.

In cases of more significant laryngeal paralysis or respiratory distress, surgical intervention is recommended. “Tieback” surgery, or unilateral arytenoid lateralization, involves tying back one side of the “curtain”/arytenoid cartilage to allow for air passage. This type of surgery significantly improves breathing and quality of life but increases the risk of aspiration pneumonia (i.e. food/water entering the lungs).

Larynx after tieback surgery

Tieback

One side of the arytenoid cartilage is tied back out of the airway. Usually the left side.

References

Rishniw, Mark et al. “Effect of doxepin on quality of life in Labradors with laryngeal paralysis: A double-blinded, randomized, placebo-controlled trial.” Journal of veterinary internal medicine vol. 35,4 (2021): 1943-1949. doi:10.1111/jvim.16162

Davies. The Veterinarian Specialists. (2022) Laryngeal Paralysis and Collapse Fact Sheet. Retrieved July 5, 2022 from https://vetspecialists.co.uk/fact-sheets-post/laryngeal-paralysis-and-collapse-fact-sheet/.

Rishniw, Mark et al. “Effect of doxepin on quality of life in Labradors with laryngeal paralysis: A double-blinded, randomized, placebo-controlled trial.” Journal of veterinary internal medicine vol. 35,4 (2021): 1943-1949. doi:10.1111/jvim.16162

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GOLPP.com