Laryngeal paralysis

What is laryngeal paralysis?

The larynx is located in the back of the throat and is otherwise known as the voice box. It also serves an important function to protect the airways from food being inhaled during swallowing. 

Laryngeal paresis or paralysis occurs when the muscles attached to the larynx cannot function appropriately. This is due to a problem with the nerves that tell the muscles to pull open the laryngeal cartilages. As a result, the larynx can no longer open as much as it should during breathing. The airway opening is narrowed and less air is able to get into the lungs. This can lead to cause significant breathing difficulties, which can quickly become an emergency situation if not controlled. 

 Causes of laryngeal paralysis

Laryngeal paralysis is a common condition, mostly affecting dogs. There are a number of potential causes, however most commonly it is idiopathic (unknown cause). It can also occur as part of a polyneuropathy, which is a progressive degenerative condition of multiple nerves, causing dysfunction in multiple parts of the body, including an enlarged oesophagus (megaoesophagus) and/or hindlimb weakness. 

Laryngeal paralysis most commonly affects middle-aged to older large breed dogs particularly Labradors, Golden Retrievers and Great Danes. In some breeds (such as Dalmatians, Huskies and Bull Terriers), there is also a congenital form of the condition that occurs earlier in life. 

Other less common causes of laryngeal paralysis include trauma, toxicity or cancerous growth usually involving the thyroid. 

Signs of laryngeal paralysis

The clinical signs of laryngeal paralysis may be subtle in many patients most of the time. The signs are often exacerbated with stress or exertion. As the disease progresses, clinical signs can become severe. 

 Signs include:

·      Noisy breathing  

·      A change in bark/meow  

·      Coughing or gagging while trying to eat or drink

·      Exercise intolerance

·      In severe cases, respiratory distress, cyanosis (blue/pale gums) or collapse

How to diagnose laryngeal paralysis

Commonly, your vet will be suspicious of laryngeal paralysis on their initial physical examination, as animals can exhibit a characteristic noisy breathing (inspiratory stridor) that is typical of laryngeal paralysis. They may also notice other signs of neurological dysfunction, including weak hind legs. 

The diagnosis of laryngeal paralysis is confirmed by performing a thorough upper airway exam. This must be performed under a light anaesthesia and the aim is to visualise the movement of the laryngeal cartilages while the patient breaths. In cases of laryngeal paralysis, movement will be absent or may appear paradoxical with breathing (moves in instead of out when taking a breath). The condition may affect just one side of the larynx, or both sides. 

Radiographs (X-rays) of the neck and chest are often recommended as they can provide useful information about whether other problems are occurring at the same time which may be associated with the condition, such as aspiration pneumonia or megaoesophagus.

Treatment and prognosis

Laryngeal paralysis is a degenerative and progressive condition, meaning over time it will continue to worsen. However, it is possible in most cases to achieve long term improvement of the patient’s comfort and quality of life. Treatment is aimed at managing the condition, rather than curing it.

In mild cases, animals may respond to conservative therapy alone. This includes environmental changes such as weight loss, controlled exercise and anti-inflammatory medication to control laryngeal swelling. However, surgical intervention is often required.

There are different surgical options, with the most common procedure being lateralisation of the arytenoid cartilage of the larynx (laryngeal tie back). This procedure pulls one side of the laryngeal cartilages outwards permanently. By doing this, the airway is opened up so air can flow into the lungs unobstructed. 

At home care

Making a cool, calm environment at home is the best thing you can do for an animal with laryngeal paralysis, regardless of their treatment.

There are some long-term changes that must be made at home for patients that have undergone surgical intervention in particular. These animals may require specific diets and feeding regimes either in the short term post-operative period, or in some cases, for life. This may include feeding chunks or balls of food slowly at a height, giving enough time for them to be swallowed properly in between. Some animals may also benefit from having their water bowl raised off the ground to face height. 

If you have a pet with laryngeal paralysis, it is important to monitor their breathing at home. These animals, with or without surgical treatment, do have a risk of aspirating food or water, which may lead to pneumonia. If you are concerned that your animal has aspirated or showing signs of pneumonia (coughing, lethargy, difficulty breathing or inappetence), then please contact the hospital immediately.