Laryngeal Paralysis: An Evidence-Based Approach to Surgical Technique:
British Small Animal Veterinary Congress 2009
Eric Monnet, DVM, PhD, FAHA, DACVS, ECVS
College of Veterinary Medicine, Colorado State University, Fort Collins, CO, USA
Laryngeal surgery is directed at removing or repositioning laryngeal cartilages that obstruct the rima glottidis. The four currently recognized surgical procedures used to correct laryngeal paralysis are:
– Unilateral or bilateral arytenoid cartilage lateralization
– Ventricular cordectomy and partial arytenoidectomy via the oral or ventral laryngotomy approach
– Modified castellated laryngofissure
– Permanent tracheostomy
– Permanent Tracheostomy
Permanent tracheostomy is a surgical option for the treatment of dogs with laryngeal paralysis. The permanent tracheostomy bypasses the upper airway obstruction without inducing any modification in the size of the rima glottidis. This surgical technique is therefore more valuable for dogs at high risk of aspiration pneumonia (myopathy, megaoesophagus, hiatal hernia, gastrointestinal disorder). Animals respond well to the treatment and owners are typically satisfied with the results although permanent tracheostomy requires long-term attention and maintenance from the owners.and, from:
THE PET HEALTH LIBRARY
By Wendy C. Brooks, DVM, DipABVP
Educational Director, VeterinaryPartner.com
The goal of surgery, whichever technique is used, is to relieve the airway obstruction permanently while maintaining the original function of the larynx (protection of the airways).
De-barking surgery is generally thought of as a surgical solution to a behavioral problem, but it is also a fair treatment for laryngeal paralysis. The usual method involves extending a long “biting” forceps down the throat and biting out the vocal folds. Obviously anesthesia is needed to do this and the fact that the surgical area is the larynx makes normal intubation for anesthesia impossible. This means either using injectable anesthesia or placing a tracheostomy (cutting a hole in the throat lower down) and intubating through that.
Removal of the vocal folds, of course, also removes the patient’s voice, reducing barking to a whisper
The hole created by the absence of the vocal folds makes for a larger airway opening and is generally large enough to relieve the obstruction. Complications of this surgery include swelling and bleeding (which can cause obstruction in themselves, though, if a tracheostomy is placed any such obstruction is bypassed), and regrowth of a webbing of vocal tissue. An alternative technique involves approaching the larynx from the outside of the throat instead of down the mouth. This method is more difficult and time consuming but has less chance of the development of webbing. A tracheostomy, if any, is allowed to heal closed.
Another surgical technique involves only biting out one vocal fold and also biting out the arytenoids cartilage on the same side. There is more bleeding with this technique and a tracheostomy becomes more desirable. Surgeries involving removing part of the larynx have been associated with a 30% mortality
rate in laryngeal paralysis patients.
Laryngeal Tieback (also called Lateralization Surgery)
This has probably become currently the most commonly performed surgery for laryngeal paralysis. It involves placing a couple of sutures in such a way as to pull one of the arytenoid cartilages backward. By repositioning one of the arytenoids, the opening of the larynx is changed (made larger). The chief
complication of this procedure stems from the fact that only a few millimeters of position change in the arytenoids are needed. If the cartilage is moved too much, the larynx cannot properly close and aspiration pneumonia becomes a substantial risk. Commonly these patients have a persistent cough after eating
or drinking. This surgery has been associated with a 14% postoperative mortality rate. (In older times, both arytenoids were tied back to create a still larger larynx but tying off both cartilages in this way was associated with a 67% mortality rate so it is no longer done).
The April 15, 2006, issue of the Journal of the American Veterinary Medical
Association published a review of 39 dogs receiving unilateral tieback as described above. Of these dogs:
– 18% developed pneumonia just after surgery. One of these 7 dogs was euthanized, the other six recovered with treatment.
– Only 2 dogs (5%) were confirmed to have developed pneumonia more than 6 months after surgery. One of these dogs had multiple episodes of recurring pneumonia.
– 28% had persistent coughing after surgery.
– 90% of owners felt their dog had improved life quality after surgery.
Hammel, S.P., Hottinger, H.A., Novo, R.E. Postoperative results of unilateral
arytenoid lateralization for treatment of idiopathic laryngeal paralysis in
dogs: 39 cases (1996-2002) JAVMA 228 (8): 1215-1220.
In this surgery, a square of the thyroid cartilage is cut (similar to a castle’s turret’s square behind which an archer might hide). This square is moved forward and reattached to create a wider laryngeal opening. A tracheostomy is frequently needed to protect from swelling. In June of 2001, the Journal of the American Veterinary Medical Association published a survey of complications in a group of 140 dogs receiving surgical treatment for laryngeal paralysis. A summary of the results is:
– Of the 140 dogs, 34% were Labrador retrievers and 80% were classified as large breed (>48 lbs).
– 82% were over 6 years of age.
– Dogs with underlying neurologic disease were 3 times more likely to die from complications associated with laryngeal paralysis.
– Factors that significantly raised the risk of dying were: increasing age, need for a tracheostomy, concurrent respiratory disease, concurrent neurologic disease, and the development of a megaesophagus.
– Overall 34% of dogs had some kind of complication from surgery. The most common complication was aspiration pneumonia (see below), which occurred in 23.6% of dogs at some point.
– Of the dogs that developed aspiration pneumonia, about 60% developed it in the first 14 days after surgery. After aspiration pneumonia, the next most common complication was respiratory distress which occurred in 5% of patients.
– Approximately 3% of dogs died during surgery or in the 24 hours following surgery.
– About 19% of the dogs in the study received temporary tracheostomies. Of these dogs, 40% had tracheostomies that were not planned and were put in as an emergency procedure. The other 60% of tracheostomies were planned as part of the laryngeal paralysis surgery. About half of the dogs that had tracheostomies had some kind of surgical complication, surprisingly more dogs died where the tracheostomy was planned vs. those where it was placed as an unplanned emergency procedure. (15 dogs had planned tracheostomies and 7 of them died, 11 dogs had emergency tracheostomies and only 1 died).
– Approximately 8% of the original 140 dogs developed complications more than 1 year after surgery.
MacPhail CM, Monnet E: Outcome of and postoperative complications in dogs
undergoing surgical treatment of laryngeal paralysis: 140 cases (1985-1998).
JAVMA 218(12): 1949-1955, 2001
And, from a discussion on VIN:
Permanent trach care is an ongoing DAILY thing that the owners must provide for their pet.
1) keeping the hair clipped (best done in the clinic to prevent shavings from getting into the trachea)
2) injecting saline 2-6 times daily into the stoma, allowing the dog to cough and then
3) cleaning the stoma.
Nebulization of sterile saline for 10min 2-4 times daily would be OK, but usually simple saline injection works well.