Dog - Laryngeal Paralysis

Introduction

Laryngeal paralysis is quite frequently initially diagnosed as a chest infection. Initial signs are virtually the same, i.e. shortage of breath, noisy breathing or a cough. However laryngeal paralysis mainly affects middle-aged and older dogs usually of medium and large size.

What are the symptoms?

These can initially be vague and varying. 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) are also usually noted. Labradors are one of the most commonly affected breeds, therefore these signs are often put down to increasing age, heart problems or bronchitis, particularly if the dog is obese. In acute cases there can be respiratory distress with cyanosis of the mucous membranes in the mouth (the gums look blue-ish), and rapid collapse.

What is the cause?

Consider the larynx or voice box as composed of a series of separate plates of cartilage which are kept in place by the laryngeal muscles. When the nerves to these do not function correctly the muscles can no longer work and the cartilages tend to collapse inwards. Respiratory (breathing) problems are often due to collapse of the arytenoid cartilage (the sides of the box) which then interferes with breathing.

What causes the nerve paralysis?

This, in the majority of cases, is unknown.

• Dysfunction of the nerve results in muscle wastage (atrophy)
• Trauma can be a cause, e.g. a severe blow to the ventral (underside) neck region
• Tumours or space occupying lesions of the neck can be a cause
• Occasionally endocrine (hormonal) causes have been implicated, e.g. thyroid dysfunction

Are some breeds more prone?

Labrador Retrievers and Setters are probably the most common breeds affected. Bouvier de Flandres, Siberian Huskies, Bull Terriers and Dalmatians can also suffer from a form which is present from birth (congenital). In breeds with the congenital condition signs may be apparent at a much younger age.

How is a positive diagnosis made?

Tentative diagnosis depends on owner history and clinical signs. Often this only involves coughing and shortness of breath. Coupled with age and breed these are unfortunately sometimes misinterpreted as due to heart or lung problems. For a positive diagnosis other tests, including x-rays, or other imaging, blood examinations and examination of the larynx with a laryngoscope are often necessary.

Is it possible to treat the condition?

Mild cases can often be controlled medically with anti-inflammatory drugs, antibiotics and respiratory dilators. In severe cases surgery is indicated and although this does carry some anaesthetic risk 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. This thus reduces the anaesthetic time.

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.