Laryngeal paralysis is a common cause of upper airway obstruction in older, large breed dogs. It occurs when the larynx (voice box) fails to adequately open when the animal is taking a breath. Laryngeal paralysis results in progressive exercise intolerance, increased respiratory effort and sounds, coughing, gagging, and voice changes. There are several causes of laryngeal paralysis, but it is most commonly referred to as idiopathic in which a known cause is not identified. Known causes of laryngeal paralysis include damage to the nerve that supplies the voice box (recurrent laryngeal) from trauma, polyneuropathy (nerve disorders) secondary to hypothyroidism or immune mediated disease, and masses or tumors in the larynx. Recent reports suggest that laryngeal paralysis is part of a broader and more generalized neurologic disorder that includes muscular weakness.
How is this diagnosed?
A thorough physical examination including palpation of the neck region and a neurologic evaluation provide necessary information regarding the overall health of the patient. A comprehensive blood test, urine analysis, and chest x-rays are performed to identify other causes of airway problems as well as the presence of concurrent medical conditions. X-rays may reveal the presence of lung changes, dilation of the esophagus and heart enlargement which may exclude dogs as surgical candidates. Laryngeal paralysis is confirmed with the pet placed under a light plane of anesthesia which allows visualization of the opening and closing of the larynx. Pets with laryngeal paralysis are not able to effectively open their larynx during inspiration. Once the diagnosis is confirmed pets are often taken directly to surgery to correct the problem.
How is laryngeal paralysis treated?
The goal of treating laryngeal paralysis is to alleviate signs of upper airway obstruction while minimizing complications thus allowing the patient to breathe more comfortably and return to an age-appropriate level of activity. This goal can be achieved through a variety of surgical methods (laryngoplasty). These include partial arytenoidectomy (removal of a portion of the airway opening), ventriculochordectomy (remove the focal folds), modified castellated laryngofissure (widening the larynx) and arytenoid lateralization or “tie-back”. Most surgeons prefer the “tie-back” surgery to address laryngeal paralysis.
Arytenoid lateralization or “tie-back”
This surgery is designed to permanently pull open one side of the larynx thus improving air flow. See illustrations. It is a technically demanding surgery in which two non-absorbable sutures are placed within very specific cartilage structures on one side of the voice box (usually the left) to abduct or open the airway diameter.
Are all patients with laryngeal paralysis candidates for surgery?
No. Pets that are not good candidates for surgery include those with existing lower airway (lung) problems such as pneumonia, megaesophagus (dilated and dysfunctional esophagus), and conditions that produce difficulty with eating and swallowing (dysphagia).
What is the prognosis with surgery?
Most pets experience a dramatic improvement in their breathing immediately following surgery. Some dogs will experience a change in their bark, as if they had been debarked. This is due to the wider opening of the airway. Some may also experience a soft cough or ‘clearing of the throat’, especially after eating and drinking. Because laryngeal paralysis can be linked to other neuromuscular conditions, we advise owners to observe for signs related to the progression of generalized neuromuscular weakness.
A very careful post-operative home program must be followed to reduce complications. One of the greatest concerns following tie-back surgery is aspiration pneumonia. Some reports estimate that up to 20-30% of post-operative patients may experience aspiration pneumonia. This is a very serious and potentially life threatening complication. The larger airway opening presents a greater risk for pets to unintentionally inhale food particles during eating. This is why it is imperative to change the manner in which pets are fed following “tie-back”surgery. We recommend feeding moistened food in the form of meatballs for the first four weeks following surgery; no dry food. Moistened food is preferred because dry food crumbles and has a greater chance of entering the airway. Food is to be fed at ground level. Water intake is to be kept normal, at ground level. Additionally, we ask that pets be placed in a chest harness during leash walking rather than in a collar to avoid further neck trauma. Swimming post-operatively is also discouraged as it is easy for dogs to inadvertently inhale water.
Our experience with surgical repair of laryngeal paralysis has been overwhelmingly positive. Our clients are often surprised at how much energy their pets have following surgery.