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LARYNGEAL PARALYSIS

First broadcast on www.provet.co.uk  


This information is provided by Provet for educational purposes only.

You should seek the advice of your veterinarian if your pet is ill as only he or she can correctly advise on the diagnosis and recommend the treatment that is most appropriate for your pet.

Laryngeal paralysis is quite common in older dogs, and it is also seen in cats - but what is it ? 

The larynx is an important anatomical structure which lies at the back of the throat in an area called the pharynx. It is responsible for controlling air flow into and out of the windpipe (trachea). When breathing in and out the larynx is open, and when swallowing food or during vomiting  muscles of the larynx contract to close off the entrance to the windpipe so that food doesn't fall down it and enter the lungs. The larynx is also the organ that uses air to vibrate soft tissue folds (the vocal cords) to produce sounds.

When nerves to the larynx (notably the vagus and recurrent laryngeal nerve) lose their function paralysis results. Signs of laryngeal paralysis include :

  • A change in voice
  • A cough 
  • Gagging or coughing when eating or drinking
  • A "roaring" noise when breathing in or out
  • Difficulty breathing (called dyspnoea)
  • Inability to exercise properly
  • The animal may turn a blue colour (called cyanosis) 
  • The animal may collapse

Laryngeal paralysis may be caused by a number of factors including :

  • Trauma to the neck
  • Damage to the nerves during surgery to remove the thyroid gland
  • Pressure on the nerves due to tumours in organs near to the nerves
  • Cancer spread to the nerves
  • Congenital (inherited) abnormalities of the nerves leading to signs of laryngeal paralysis in dogs under 1 year of age. Reported to occur in Bouvier de Flandres (Holland), Bulldogs (UK) and Siberian Huskies (US).
  • In Dalmatians it is seen in young dogs and is associated with a polyneuropathy.

However, in the majority of  case the underlying cause remains unknown and this is called idiopathic laryngeal paralysis. It occurs most frequently in dogs over 9 years of age, and some breeds (Golden Retrievers, Labrador Retrievers, St Bernards and Siberian Huskies) are predisposed to develop it. 

In the most common forms of the disease both sides of the larynx are paralysed but it can involve just one  side.

The diagnosis can be confirmed by veterinary examination of the larynx during breathing - sometimes this can only be done under a general anaesthetic.

Medical management of these cases involves the administration of oxygen (when breathing difficulty is present) and drugs (diuretics) to remove any fluid accumulation in lungs. Unfortunately, inhaled food and drink can cause pneumonia in the lungs which can be difficult to treat because of the foreign material blocking the airways. Antibiotics are required if pneumonia is present.

Various surgical techniques can be used to keep the larynx open to improve breathing. One consequence of these procedures is that the larynx is permanently open, so there is a risk of inhalation of food or drink. However, the well-being and quality of life of the animal is greatly improved because breathing is easier.

In some cases the nerve supply to the larynx can regenerate restoring normal function, and various surgical techniques have been tried to recreate nerve innervation to a paralysed larynx, but these are only available in a few specialist centres, and the results are variable

 

.Updated October 2013