Laryngeal paralysis in dogs: symptoms and treatment

Overview

The larynx, or voice box, sits at the entrance to the airway and regulates airflow into the windpipe. It closes during swallowing to prevent food and water entering the airways. Paralysis may affect one or both sides. Paralysis on one side often causes no symptoms.

When both sides are paralysed, airway narrowing usually causes more obvious symptoms. The condition is common in dogs and rare in cats. Symptoms of acquired disease can worsen over months or years. Mild disease may initially be managed with lifestyle changes and monitoring.

Surgery can ease breathing and improve quality of life. However, it does not restore normal laryngeal function.

In a study of 250 dogs undergoing general anaesthesia, 25% had evidence of varying degrees of paralysis. Airway narrowing can eventually progress to complete obstruction.

Causes

Usually, the nerve supply to the muscles that open the larynx deteriorates. Non-functioning structures may be drawn inwards by airflow during inhalation. The narrowed airway makes breathing harder. The disease can develop later in life or be congenital.

In older dogs, laryngeal paralysis is often part of more widespread peripheral nerve degeneration. This syndrome is abbreviated to GOLPP. Its precise underlying cause is not fully understood. Laryngeal symptoms may be the first sign noticed.

Oesophageal function can also deteriorate early in the disease. Neck injuries or tumours can also cause laryngeal paralysis. Nerve damage during surgery is another possible cause of acquired paralysis. Congenital paralysis in a young dog may be associated with generalised polyneuropathy.

The muscle that opens the arytenoid cartilages normally contracts during inhalation. Its nerve supply comes through the recurrent laryngeal nerve, which branches from the vagus nerve. Damage to the muscle itself, as well as to the nerve, can cause paralysis.

Risk factors

The disease is most often diagnosed in large dogs beyond middle age or in old age. Labrador Retrievers are among the most commonly affected breeds. Golden Retrievers and St Bernards have also been overrepresented among patients. Acquired paralysis is diagnosed more often in males than in females.

Excess weight worsens symptoms. Heat, humid weather, exercise and excitement can trigger a breathing crisis. The congenital form can cause symptoms as early as three months old. Paralysis associated with congenital polyneuropathy usually begins before one year of age.

Congenital forms have been found in breeds including Rottweilers and Siberian Huskies. A genetic variant predisposing to laryngeal paralysis is known in Miniature Bull Terriers. It does not explain every case in the breed.

Afghan Hounds and Irish Setters are also among breeds reported more often in affected dogs. Overheating is possible even during boisterous play on a cool day.

Typical symptoms

Signs you may notice at home include:

• A bark that becomes hoarse or harsh.

• Unusually loud rasping or whistling on inhalation.

• Panting at rest or even in cool surroundings.

• Tiring more easily on walks.

• Gagging or coughing when eating or drinking.

• Reduced tolerance of heat.

• Regurgitating food into the mouth or out of it.

Early symptoms can be very subtle. Slowing down during exercise may be mistaken for ageing alone. In severe cases, the chest moves forcefully and the dog looks distressed. Advanced polyneuropathy may cause limb weakness or uncoordinated movement.

Swallowing can become difficult as oesophageal function deteriorates. Vomiting can occur alongside regurgitation.

Complications and consequences

Airway obstruction can lead to oxygen deprivation. Severe obstruction can also cause pulmonary oedema. Reduced protection of the airway during swallowing increases the risk of inhaling food or fluid. This can lead to aspiration pneumonia, a lung infection associated with inhaled material.

Aspiration pneumonia can develop in dogs with or without surgery. The risk remains lifelong after surgery. Aspiration pneumonia has been reported in 8–33% of dogs after surgery. Repeated severe pneumonia can worsen the overall outlook.

Reflux of stomach fluid into the oesophagus or throat has been found in up to 62% of dogs with laryngeal paralysis. Reflux increases the risk of inhaling stomach contents when airway protection is poor. Arytenoid cartilages rubbing against one another can become swollen and inflamed. Swelling can worsen obstruction of an already narrowed airway.

The underlying peripheral nerve disease may continue to progress after surgery. The outlook differs between isolated hereditary laryngeal paralysis and more widespread congenital polyneuropathy.

Various complications have been reported in 10–34% of dogs after tie-back surgery. Symptoms have been reported to recur in 4–8% of patients. In a comparison of standard and tissue-sparing techniques, pneumonia occurred in 7% and 17% of dogs respectively. The difference in pneumonia risk was not statistically significant.

In the same surgical comparison, 16% of deaths were associated with neurological deterioration. Unrelated causes accounted for 59% of deaths.

Diagnosis at the vet

Examining laryngeal movement under light anaesthesia

The vet assesses the dog's breathing and general condition alongside the history. A neurological examination is also needed to assess more widespread nervous system disease. Diagnosis is confirmed by observing laryngeal function under light anaesthesia. Anaesthesia that is too deep can make even a healthy larynx appear paralysed.

Healthy arytenoid cartilages and vocal folds move apart during inhalation. With paralysis, they remain still or move in the wrong direction relative to breathing. Paradoxical, or opposite-direction, movement has been reported in up to 45% of patients. Movement alone therefore does not demonstrate normal function.

The vet must be able to secure breathing with a breathing tube if necessary. Recovery from the examination is monitored particularly closely. The phase of breathing is considered when interpreting the findings.

Imaging and further tests look for other problems

An X-ray does not confirm laryngeal paralysis. Chest X-rays can instead check for aspiration pneumonia. They can also reveal an enlarged oesophagus. Imaging investigates masses in the neck and mediastinum.

Thyroid tests may be needed if other symptoms suggest hypothyroidism. Acetylcholine receptor antibodies are tested if myasthenia gravis is suspected. An elongated soft palate can cause similar symptoms. Other causes to distinguish include tracheal collapse, inflammation and a foreign body.

An ACTH stimulation test may be performed if Addison's disease is suspected. Electromyography can show changes consistent with nerve supply damage. Laryngeal ultrasound can also be used in diagnosis.

Treatment

Stabilising a breathing crisis comes first

During an acute breathing crisis, the dog often needs supplemental oxygen. An overheated patient is cooled. The vet may use sedation to reduce panic and breathing effort. Severe obstruction may require a breathing tube and assisted ventilation.

If breathing cannot otherwise be secured, a tracheostomy may be performed. Fluid therapy takes account of the risk of pulmonary oedema associated with severe upper airway obstruction. Further breathing crises can occur after emergency treatment if the narrowing is not corrected.

Mild disease can be managed conservatively

A mildly affected dog's daily routine is kept calm, with moderate exercise. Weight loss can ease symptoms in an overweight dog. A harness replaces the collar. Exertion in hot, humid weather is limited.

Physiotherapy may help maintain muscle mass and function. The vet may prescribe medication to reduce anxiety when needed. Confirmed aspiration pneumonia is treated with antibiotics. No medicine is known to cure laryngeal paralysis.

Surgery widens the airway on one side

Surgery is recommended when breathing symptoms significantly impair quality of life. The most common procedure is unilateral arytenoid lateralisation, also called tie-back surgery. A suture holds one arytenoid cartilage in a more permanently open position. Widening one side is sufficient for most dogs with paralysis on both sides.

Excessive widening can reduce protection against food entering the airways. Other surgical options in selected cases include tissue removal or a permanent tracheostomy. Improved respiratory symptoms, exercise tolerance and quality of life have been reported in around 90% of dogs undergoing surgery.

A surgical comparison involving 80 dogs examined standard and tissue-sparing tie-back techniques. Median survival after the standard technique was 636 days. After the tissue-sparing technique, it was 1,067 days. The difference in survival between groups was not statistically significant.

After surgery, food is initially offered as soft, easy-to-swallow mouthfuls. Water is offered in small amounts while swallowing is observed. Barking is usually restricted for six weeks. A fluid pocket, or seroma, can develop at the surgical site.

Failure of the tie-back suture can cause breathing difficulties to return. The risk of suture failure is greatest during the first two to three weeks. Repeat surgery on the other side has been needed in around 5% of patients.

Prevention

Some DNA tests are available for breeds predisposed to congenital forms. Testing for the known LP risk allele in Miniature Bull Terriers can help avoid breeding combinations at risk. A carrier with an N/LP result has one known risk allele. On average, a carrier passes this allele to 50% of their offspring.

An LP/LP result, indicating two risk alleles, means an increased risk of disease. Even such a dog may remain symptom-free. The genetic test does not rule out other, as yet unknown, inherited risk factors in the breed.

When planning to breed Miniature Bull Terriers, testing for the known genetic risk factor is recommended before mating.

Important for dog owners

Laryngeal paralysis requires lifelong monitoring. Swimming is avoided after surgery to reduce the risk of inhaling water. Water and soft food are offered in small portions. Mild coughing may occur after eating or drinking.

Record changes in breathing sounds, barking, walking and swallowing. Also tell the vet about hindlimb weakness and regurgitation. Follow the operating vet's feeding and exercise instructions.

A new persistent cough, loss of appetite, fever or tiredness requires prompt assessment for pneumonia. Mobility may continue to deteriorate even if surgery improves breathing. Rehabilitation can support muscle strength as the disease progresses.

Agree with the treating vet whom to contact if another breathing crisis occurs. At home, also assess whether your dog can eat, sleep and go outside without obvious breathing effort.

Frequently asked questions

Is laryngeal paralysis the same as slowing down with age?

Slowing down may result from insufficient airflow through the larynx. A hoarse bark and harsh breathing are possible early signs. Diagnosis is confirmed by examining laryngeal function under light anaesthesia. Other possible signs include coughing and gagging while eating.

Does surgery cure laryngeal paralysis?

Surgery widens the airway but does not restore normal laryngeal function. Often, only one side is held more open. The underlying polyneuropathy may continue to progress after surgery. Improved quality of life and exercise tolerance have been reported in around 90% of dogs undergoing surgery.

Why is heat dangerous for an affected dog?

Dogs use breathing to cool their bodies. Laryngeal paralysis predisposes them to overheating even with relatively mild exertion. Hot, humid weather can trigger a sudden breathing crisis. Bluish mucous membranes or collapse with breathing difficulties particularly require immediate veterinary help.

Can a dog swim after surgery?

Swimming is avoided because water can enter the airways through the more open larynx. The risk of aspiration pneumonia remains despite surgery. Water and soft food are offered in small portions while swallowing is monitored. Persistent coughing or fever requires veterinary assessment.

Does a normal genetic test mean a dog cannot develop the disease?

No: the available tests cover particular inherited risk factors in particular breeds. The known LP risk factor in Miniature Bull Terriers does not explain all cases. Other, as yet unknown, inherited factors also occur in the breed. In older dogs, paralysis is often associated with more widespread polyneuropathy.