What is Laryngeal Paralysis?
For most older dogs, Laryngeal Paralysis (LP) occurs due to an aging process of the nerves that supply the laryngeal muscles and cartilages. The larynx (voice box) is the first part of the upper airway and is made up of 5 cartilages. The epiglottis cartilage flips upwards and protects the entrance of the airway (the glottis) during swallowing and the paired arytenoid cartilages function to open and close like a pair of curtains as the patient breathes in and out. If the arytenoid cartilages are paralysed or partially paralysed, they will hang in the entrance of the airway (the glottis) and obstruct airflow. The patients develop a raspy breathing noise and over time, usually months they become less able to cope with exercise. Any slight exertion or excitement can potentially leave these dogs in a very compromised state, they struggle to breathe, it can be a life threatening situation.
Who is affected?
Laryngeal Paralysis of the older dog can occur in any breed but at Northwest Surgeons, we tend to see this condition mostly in large breed dogs. The most common breeds to present are Labradors and Golden Retrievers but we have seen the Greyhound, Rhodhesian Ridgeback, Hungarian Visla, Leonberger and a Bouvier de Flanders breeds during the past year.
What should we look for?
A gradual onset of noisy breathing, not coping with exercise , having to excessively pant, tongue and gums turning a purple colour (cyanosis) during periods of stress, throat clearing and the pitch of the bark may also alter with time.
How do we confirm the diagnosis?
Laryngeal function cannot be assessed in the conscious patient, so we have to try and view the larynx moving at a point which most represents its function in real life. We do this by viewing the larynx moving as the patient is given a small amount of intravenous anaesthetic, just enough to slacken the jaw tone but to minimally affect the patients attempts to move their arytenoid cartilages. At Northwest Surgeons we usually record these images to demonstrate to the patient’s owners the degree of LP.
How do we treat Laryngeal Paralysis?
A non surgical / conservative approach can be taken for those patients who may have a number of medical conditions, are too debilitated to undergo anaesthesia or where finance precludes a surgical treatment. We would normally advise that these dogs use a harness for exercise restraint and are only walked in cooler weather. It is worth considering the purchase of a mobile air conditioning unit, so that one area of the house can be made very cool on humid and hot days – we find this is a very useful aid to cool and reduce the stress that hot weather can cause to patients with LP. Medications such as anti-inflammatories can be useful to reduce the inflammation that surrounds the larynx.
The aims of surgery
- Increase the size of the aperture leading into the airway (the glottis) allowing easier breathing
- Preserve airway protection
The larynx is approached surgically from the left side of the neck. Careful dissection between the muscles of the neck and larynx gives access to the paralysed left arytenoid cartilage. This cartilage is then carefully mobilised from the surrounding chassis of the larynx and re positioned so that it sits to one side – it has been ‘tied-back’ (lateralised). This cartilage is secured into its new position by two small but very strong sutures that do not dissolve.
Following surgery, owners are advised to make sure their dog eats slowly by hand feeding or incrementally feeding small amounts at any one time. This limits the patients bolting their food, coughing during eating and hence reduces the risk of sucking back food particles into the airway. Aspiration pneumonia is an uncommon complication for LP surgery providing the feeding protocol is adhered too for at least 4 weeks post surgery.
Future advances in the treatment of laryngeal paralysis include the use of lasers to partially ablate one side of the paralysed cartilage and the use of stents to fortify the weakened cartilage of the larynx.
Laryngeal paralysis in the older dog is a common condition that we see at Northwest Surgeons. For most patients, surgical intervention results in a significant improvement in their ability to breathe. These older patients can then resume the activities they enjoy without the constant concern of an ensuing respiratory crisis.
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