Laryngeal Paralysis

Laryngeal paralysis is probably more common than generally recognised. It affects middle aged and older dogs, usually of medium and large size. This is because initially symptoms often only involve a shortage of breath, noisy breathing or a cough. Consequently the condition is at first frequently diagnosed as a chest infection.

What are the symptoms?

Presenting signs vary. Coughing, particularly after exercise is probably the most usual together with noisy breathing, exercise intolerance and a change in the sound of the bark (dysphonia). Labradors are one of the most commonly affected breeds, therefore these signs are often put down to increasing years, heart problems or bronchitis, particularly if the dog is obese. In acute cases there can be respiratory distress with a blueness of the mucous membranes (cyanosis) in the mouth and rapid collapse.

What is the cause?

The larynx or voice box is composed of a series of separate plates of cartilage whose dimensional stability is maintained by the laryngeal muscles. When the nerves of these muscles become paralysed the muscles no longer work and the cartilages tend to collapse inwards. The respiratory problems are generally due to collapse of the arytenoid cartilage which then interferes with breathing.

What causes the paralysis?

In the majority of cases the cause is unknown. The nerve paralysis results in the muscles wasting (atrophy). Trauma can sometimes be a cause, e.g. a severe blow to the ventral neck region. Tumours or space occupying lesions in the neck or chest area have also been implicated and occasionally endocrine causes may be involved, e.g. thyroid dysfunction.

Is the condition more common in any particular breed?

Setters and Labrador Retrievers are probably the most common breeds suffering from the idiopathic form. There is also a congenital form (present from birth) involving Bouvier de Flandres, Siberian Huskies, Bull Terriers and Dalmatians. In these breeds onset may be at a much younger age.

How is a positive diagnosis made?

Tentative diagnosis depends on owner history and clinical signs. Coughing and shortness of breath are often the only initial signs. Coupled with age and breed these are often misinterpreted as due to heart or lung problems. Therefore other tests, including radiography and blood examinations are often necessary. Confirmation depends on laryngoscopy. The dog is lightly anaesthetised and the larynx and vocal cords examined with a special instrument.

"Coughing and shortness of breath are often the only initial signs. Coupled with age and breed these are often misinterpreted as due to heart or lung problems."

Is it possible to treat the condition?

Mild cases can often be controlled medically with anti inflammatory drugs, antibiotics and respiratory dilators. However in severe cases surgery is indicated and although this does carry some risk in view of the anaesthetic, it can be extremely successful.

What does surgery involve?

Various techniques are available, depending on the severity of the condition. The most popular surgical treatment today involves arytenoid lateralisation by “tie-back”. This involves tying the collapsed cartilage to the side of the larynx so it does not cause an obstruction to breathing. This in many cases will give an ageing, obese, severely distressed dog a new lease of life. Although the arytenoid cartilages are usually both affected it has been found that tying back of one cartilage is sufficient to relieve the signs.

Is any other treatment required?

It may be necessary to restrict exercise, particularly in hot weather and to use a harness instead of a collar and lead. We will be more than happy to discuss these and any other concerns or queries with you. Please do not hesitate to contact us.