What is laryngeal paralysis?
Laryngeal paralysis is the term used to describe a functional failure of the larynx (voice box), particularly a failure to open the vocal cords during inspiration (breathing in).
Why is the larynx important?
The larynx has three main functions:
All three functions are important to our pets but the first two are the most significant in terms of airway maintenance. Correct laryngeal function is therefore critical for providing and maintaining a properly functioning entrance to the trachea (windpipe).
What breeds are affected?
Whilst there are some reports of congenital laryngeal paralysis which affects young dogs less than a year old, the majority of cases develop later and affect middle-aged to older animals. Most cases presented to veterinary surgeons occur in dogs rather than cats, and particularly affects larger breeds such as Labrador Retrievers, Golden Retrievers, Weimeraners, Bernese Mountain Dogs, Great Danes etc., although smaller dogs and cats can be affected.
What are the signs of laryngeal paralysis?
The signs of laryngeal paralysis include:
Unfortunately, left untreated this condition is often life-threatening. If you have any concerns at all that your dog may be showing any of the signs listed above, please visit your primary care vet to seek advice and referral if necessary.
What are the causes of laryngeal paralysis?
The signs associated with laryngeal paralysis are usually caused by a dysfunction of one or both recurrent laryngeal nerves. These nerves supply the muscles that are responsible for holding the vocal cords open during inspiration (breathing in) and therefore failure to work effectively can result in partial obstruction of the upper airway. Often, these nerves are not the only ones affected and therefore incoordination or failure of function of nerves supplying other parts of the larynx (voice box) can contribute to food or water gaining access to the airway during swallowing and altered phonation (barking/mewing).
The more common causes of laryngeal paralysis include:
How is laryngeal paralysis investigated?
The veterinary surgeon may have a strong suspicion of the diagnosis of laryngeal paralysis from the age and breed of the patient, the sound of the respiratory pattern and discussion of the history with the owner.
A full clinical examination, including neurological assessment, is important early in the investigation of this disease.
Definitive diagnosis usually requires careful examination under general anaesthesia by an experienced veterinary surgeon. Unfortunately, recovery from general anaesthesia is associated with increased risks if an animal is suffering from laryngeal paralysis, and therefore definitive diagnosis is usually made immediately before surgical treatment is carried out under the same anaesthetic.
Before induction of general anaesthesia to definitively diagnose and treat the condition, it is important to carry out a number of checks in order to decide on the likely cause of the condition and therefore help in deciding whether surgical treatment is appropriate. The investigation will commonly involve:
What are the treatment options for laryngeal paralysis?
The most effective and commonly performed surgical treatment for laryngeal paralysis is called a ‘Tieback’ or Unilateral Arytenoid Lateralisation (UAL). This involves permanently fixing one of the patient’s vocal cords in an open position.
What is the prognosis for dogs showing signs of laryngeal paralysis?
Approximately 90-95% of animals undergoing a tieback procedure have a significantly improved airway and, therefore, improved quality of life following the procedure.
Complications that can occur in the minority of cases include:
Permanently holding one of the vocal cords open can greatly improve the airflow in an animal suffering complete paralysis of both sides of the larynx. Unfortunately, the procedure will also reduce the patient’s ability to cough effectively, and may also increase the risk of food and drink gaining access to the airway. The potential for aspiration pneumonia and complications resulting from surgery involving structures of the airway result in the requirement for careful investigation of the patients and careful discussion with the owner before surgery.
What if I decide not to have the procedure performed on my animal?
Laryngeal tieback surgery is usually only performed on animals suffering clinical signs and often only on animals suffering bilateral paralysis. Those animals not receiving surgery must be monitored very closely indeed for signs of deterioration in function or aspiration pneumonia and these patients MUST avoid heat stress.
Unfortunately, once diagnosed the condition is usually progressive and so there will always be a degree of anxiety when considering those cases with some remaining function of the recurrent laryngeal nerves. These animals may still have some function of the larynx but are at risk of deterioration in the future. The decision regarding when to operate is usually based on an assessment of the risks and benefits associated with surgery and the potential for sudden severe decompensation without surgery. This decision is made on a case-by-case basis and detailed discussion with the specialist veterinary surgeon is advised.
What should I do after the procedure to help manage the condition?
There are several management changes that can make a significant contribution to ongoing success following a laryngeal tieback procedure:
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