Laryngeal paralysis

What is ... ?: 

 In this disorder, there is some loss of function in the laryngeal muscles that normally open the larynx when an animal breathes in. This is caused by degeneration of certain nerves involved in normal breathing. The result is airway obstruction, to varying degrees, causing loud and labored respiration.
 
In the Dalmatian, this condition is part of a more widespread condition of the nervous system called laryngeal paralysis-polyneuropathy complex.
In the inherited form, signs are usually seen before 6 months of age. Laryngeal paralysis due to other causes is also seen in older dogs of other breeds.
 

How is ... inherited?: 

In the Bouvier and the Siberian husky, inheritance is autosomal dominant. In the Dalmatian it is autosomal recessive.

What does ... mean to your dog & you?: 

 Signs of this disorder are usually seen by 2 to 6 months of age and are often first noticed, or become worse, in hot weather. Affected dogs have difficulty breathing, and may collapse, especially with exercise. Your dog's breathing will be noisy, with coughing or gagging when eating, and you may notice that the gums are greyish rather than pink.
 
As part of the laryngeal paralysis-polyneuropathy complex, affected Dalmatians commonly have megaesophagus, which is a chronic dilation (expansion) of the esophagus that occurs due to loss of normal muscle tone and function, so that swallowing can not occur normally. Affected dogs regurgitate undigested food after meals, and may develop aspiration pneumonia due to inhalation of food particles or other foreign matter.
 

How is ... diagnosed?: 

 Your veterinarian will suspect a problem of airway obstruction based on what you describe and on your dog's breathing pattern. Laryngoscopy (looking down your dog's throat with a light) will confirm laryngeal paralysis as the cause.
 
 

 

How is ... treated?: 

 Initial treatment is aimed at calming your dog and lessoning repiratory distress. Depending on the severity of the obstruction, this may require mild sedation, administration of oxygen, and low doses of corticosteroids to reduce swelling. Rarely, with very severe breathing problems, a veterinarian may need to put a tube into a dog's trachea (an emergency tracheostomy).
 
Once your veterinarian has assessed your dog, s/he will discuss with you management of this condition. In mild cases, all that may be required is avoidance of stress, especially associated with exercise and heat, and occasional medical treatment as above for episodes of respiratory distress. Where the condition is more severe, your veterinarian may suggest surgery to tie back the muscles and enlarge the opening of the larnyx.
Unfortunately the outlook is guarded to poor for Dalmatians with laryngeal paralysis-polyneuropathy complex. Most die or are euthanized within a few months of diagnosis, due to aspiration pneumonia.
 

For the veterinarian: 

 Laryngeal function can best be assessed when the dog is very lightly anesthetized. On inspiration one or both vocal folds will not abduct normally, and the glottis will collapse.  Electromyography can be used to test the function of the laryngeal muscles.
 
Other neurologic signs in Dalmatians with laryngeal paralysis-polyneuropathy complex may appear before, at the same time as, or after the development of signs relating to respiratory distress. Signs of neurologic dysfunction may include hyporeflexia, proprioceptive deficits, hypermetria, and paresis. Megaesophagus is common in these dogs.
 

Breeding advice: 

 Affected dogs should not be bred. In the Bouvier and husky, where inheritance is autosomal dominant, close relatives should be carefully evaluated for signs of this problem before being used for breeding.
 
Due to the autosomal recessive mode of inheritance in the Dalmatian and possibly the bull terrier, breeding of the parents (carriers of the disorder) and siblings (suspect carriers) should be avoided.
FOR MORE INFORMATION ABOUT THIS DISORDER, PLEASE SEE YOUR VETERINARIAN.
 

Resources: 

 Braund KG. 1995. Peripheral nerve disorders. In EJ Ettinger and EC Feldman(eds.) Textbook of Veterinary Internal Medicine, p. 701-726. WB Saunders Co., Toronto.

 Braund KG. 1995. Laryngeal paralysis-polyneuropathy complex in young dalmatian dogs. In JD Bonagura and RW Kirk(eds.) Kirk's Current Veterinary Therapy XII Small Animal Practice p. 1136-1140. WB Saunders Co., Toronto.

Bjorling DE. 1995. Laryngeal paralysis. In JD Bonagura and RW Kirk(eds.) Kirk's Current Veterinary Therapy XII Small Animal Practice. p. 901-901. WB Saunders Co., Toronto.


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