Laryngeal Paralysis

This is a condition where the larynx fails due to the inability to abduct the arytenoid cartilages during inspiration. The illness is more pronounced when a dog is exercising, hot and panting. You’ll notice a harsh noisy sound, particularly on inspiration. It can significantly reduce an animal’s exercise tolerance, and if not controlled, the airways can become so restrictive that the obstruction can be life threatening. We usually come across it in middle aged to older dogs of medium to large breeds such as Labradors, Retrievers and Weimaraners. It can be either congenital or acquired, with the most common form of the disease being geriatric onset laryngeal paralysis polyneuropathy.

Posted: 12 August 2019

Laryngeal Paralysis

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What are the signs of laryngeal paralysis?

Laryngeal paralysis a progressive condition, gradually and slowly worsening over months or years. Look out for some or all of these signs;

  • Increased inspiratory noise - loud rasping noise when breathing in
  • Coughing – a loud, harsh unproductive cough
  • Voice change – sometimes owners will notice a change in the dog’s bark, often becoming higher pitched and squeaky.
  • Difficulty swallowing food and or water – you may notice choking on food when swallowing.
  • Exercise intolerance – dogs will be less inclined to run and play or go on long walks.
  • Collapse – in extreme cases dogs may become cyanotic, with blue lips and tongue through lack of oxygen.
  • Weight loss – many dogs can become exhausted through the effort of breathing, and as a result will lose weight
  • Reduced exercise tolerance – restricted airways results in reduced oxygen availability when exercising
  • Reduced temperature tolerance – great care should be taken with dogs in hot weather as they find it hard to pant and lose heat

What causes laryngeal paralysis?

In the majority of cases it occurs as a result of a conduction failure of the nerves that control normal laryngeal function. The exact cause is unknown but it is considered an age related issue. Occasionally the problem happens as a result of injury or trauma, resulting in nerve damage.

The more common causes of laryngeal paralysis include:

  1. Peripheral polyneuropathy - the recurrent laryngeal nerves become ineffective due to pathological changes. A neurological examination may reveal subtle signs of nerve dysfunction elsewhere in the body. The exact cause of this is frequently unknown.
  2. Trauma – crushing, entrapment of tearing of the recurrent laryngeal nerves from trauma or pathology can lead to poor or absent function.
  3. Iatrogenic – surgery in the neck region (e.g. from thyroid gland removal) can result in unavoidable damage.
  4. Neoplasia – a space occupying mass affecting the neck or anterior thoracic cavity can result in pressure on the recurrent laryngeal nerves.
  5. Hormonal changes – poorly controlled hypothyroidism may cause a peripheral neuropathy with laryngeal nerve dysfunction.

How is laryngeal paralysis diagnosed?

The breed and age of the dog are often highly suggestive of laryngeal paralysis, but you will need to confirm the diagnosis by using a light anaesthetic to look at the vocal folds in action. Blood tests to check for other diseases and a chest x ray to rule out neoplasia and pneumonia are often suggested. A full clinical examination, including a neurological assessment, is important early in the investigation of this disease.

Definitive diagnosis usually requires careful examination under general anaesthesia. It’s important to carry out a number of checks to confirm whether surgical treatment is appropriate. The investigation will commonly involve;

  • Blood samples – to check organ function and signs of a thyroid dysfunction
  • X-rays – to check for signs of pneumonia, megaoesophagus or tumours which may alter the prognosis
  • Ultrasound – a scan of the neck can sometimes be helpful
  • Electro-myogram (EMG) - an electrical nerve and muscle test, in cases where a generalised polyneuropathy is suspected

How do we treat laryngeal paralysis?

A. Laryngeal tieback surgery

The most effective and commonly performed surgical treatment for laryngeal paralysis is called a ‘Tieback’ or Unilateral Arytenoid Lateralisation (UAL). This surgery holds one of the vocal folds in an open position making it easier to breathe without obstruction. Surgery is usually very successful, with over 90% showing significant improvement.

B. Conservative management

For cases that are not too severe or who’s’ owners don’t want to rush to surgery, there are some effective ways to minimise the symptoms. This can be achieved by;

  • Diet – overweight animals always suffer more, so encourage the owner to keep their dog slim and trim.
  • Use a harness – avoid collars and leads, as these will put pressure onto the trachea.
  • Stay cool – keep the dog away from hot and humid conditions. In very hot weather, which we seem to be more prone to these days, there are a variety of cooling tips that can be offered.

It’s important to keep the owner informed on the prognosis, as they should all be aware that their pet may deteriorate suddenly without warning.

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