Laryngeal Paralysis
Why Should I Bring my Pet to Willows for Treatment of Laryngeal Paralysis?
Willows is one of Europe’s leading small animal referral centres. Our state-of-the-art hospital is led by internationally renowned Specialists, committed to providing the highest standards of veterinary care. Our Soft Tissue Specialists have a particular interest and extensive experience in the treatment and management of patients with laryngeal paralysis.
Our team of Surgeons are supported by our multi-disciplinary team of Specialists across a number of disciplines including; Anaesthesia, Diagnostic Imaging and Emergency and Critical Care. Willows also has a large dedicated team of Vets, Nurses and clinical support staff available 24 hours a day, every day of the year to provide the best possible care for your pet.
What is Laryngeal Paralysis?
Laryngeal paralysis is a functional failure of the larynx (voice box), in particular a failure to open the vocal cords during inspiration (breathing in). The larynx has three main functions:
- To open the vocal cords during inspiration (breathing in) to facilitate adequate air flow
- To snap the vocal cords shut during swallowing to prevent food and water entering the windpipe
- To allow vocalisation (e.g. barking) during expiration (breathing out)
All functions are important, however the first two are the most significant in airway maintenance. Correct laryngeal function is therefore critical for providing and maintaining a properly functioning entrance to the trachea (windpipe).
What are Most Common Causes of Laryngeal Paralysis?
The signs of laryngeal paralysis are usually caused by a dysfunction of one or both recurrent laryngeal nerves.
These nerves supply the muscles that hold the vocal cords open when breathing in, and 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 voice box can contribute to food or water gaining access to the airway during swallowing and altered barking/mewing.
The most common causes of laryngeal paralysis include:
- Peripheral polyneuropathy (generalised nerve dysfunction); the recurrent laryngeal nerves are among the longest in the body and very susceptible to diseases that reduce their ability to conduct impulses.
- Trauma; to the recurrent laryngeal nerves can lead to poor or absent function
- Latrogenic; resulting as a complication or result of medical treatment. Neck surgery (e.g. thyroid gland removal) can result in unavoidable damage to the nerves supplying the larynx
- Tumours; affecting the neck or front of the chest can place pressure on the nerves causing them to malfunction
- Hormonal disturbances; poorly controlled hypothyroidism (under-active thyroid gland) can cause a peripheral neuropathy and can be a possible cause of laryngeal nerve dysfunction.
What are the Signs of Laryngeal Paralysis?
The signs of laryngeal paralysis include:
- Increased inspiratory noise (loud rasping noise during breathing in)
- Coughing
- Weight loss
- Reduced exercise tolerance
- Collapse
- Reduced tolerance of increased temperature (less able to pant)
- Altered phonation (bark/mew sounds different)
- Problems swallowing food and/or water (coughing and spluttering)
- Sudden respiratory distress, particularly when subjected to a warm environment
If left untreated this condition can unfortunately be life threatening. If you have any concerns at all that your dog may be showing any of the signs listed above, please seek advice from your local vet.
How is Laryngeal Paralysis Diagnosed?
Laryngeal paralysis can be strongly suspected from the age and breed of the patient, the breathing 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 examination under general anaesthesia. Recovery from general anaesthesia is associated with increased risks for patients suffering from laryngeal paralysis. As such, once a definitive diagnosis is made, surgical treatment will be immediately carried out under the same anaesthetic.
A number of checks will be carried out before the general anaesthesia to identify likely causes of the condition and decide if surgical treatment is appropriate. The investigation will usually involve:
- Blood samples; to check organ function and for signs of thyroid dysfunction
- X-rays; to check for signs of pneumonia and megaoesophagus (enlarged food pipe) or tumours which may alter the prognosis
- Ultrasound; a scan of the neck can sometimes be helpful
- Electro-myogram (EMG); electrical nerve and muscle test, in cases where a generalised polyneuropathy is suspected
What are Treatment is Available for Laryngeal Paralysis?
The most effective and commonly performed surgical treatment for laryngeal paralysis is a ‘Tieback’ or Unilateral Arytenoid Lateralisation (UAL). This involves permanently fixing one of the vocal cords in an open position.
What can I Expect if my Pet undergoes Treatment for Laryngeal Paralysis?
Approximately 90-95% of patients that undergo a ‘tieback’ have a significantly improved airway and quality of life. Permanently holding one of the vocal cords open can greatly improve the air flow in a patient suffering paralysis of both sides of the larynx. The procedure can however result in complications in the minority of cases and may include:
- Haemorrhage (bleeding)
- Airway swelling
- Infection
- Aspiration pneumonia; infection of the lungs caused by food/water passing through the larynx
- Seroma formation; fluid build-up in the loose neck tissue, usually of little clinical significance
- Suture failure or cartilage fracture; this will result in failure of the procedure.
Laryngeal tieback surgery is usually only performed on patients suffering clinical signs and often only those suffering bilateral paralysis.
For patients who do not undergo surgery, very close monitoring is required to identify signs of deterioration in function or aspiration pneumonia and these patients MUST avoid heat stress.
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 voice box, but are at risk of deterioration in the future. The decision to operate is usually based on assessment of the risks and benefits associated with surgery and the potential for sudden severe decompensation without surgery.
Long-term Management
There are a number of changes that can be made that will make a significant contribution to ongoing success following a laryngeal tieback procedure:
- Never use a neck collar for restraint or to lead walk your dog (a harness should be used)
- Avoid dry, dusty food which may be more prone to being breathed in
- Avoid heat stress – patients that have had tieback surgery still have a degree of compromise to their upper airway and should never be allowed to become stressed by heat
- Monitor your pet for signs of sickness or attempts to cough that may indicate pneumonia – consult a veterinary surgeon if you are at all concerned.
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