The larynx is the guardian of the airways, keeping whatever we want to swallow out and directing air in. Laryngeal paralysis is a condition recognized mostly in larger, older dogs that can develop slowly over a year or more until it reaches a stage that causes significant breathing emergencies. The opening to the trachea (“wind pipe”) normally is pulled open on two sides when breathing in, and then these cartilages relax when breathing out. With laryngeal paralysis, the muscles that normally pull these open do not function properly. This means no expanding and opening of the larynx for a deep breath; the laryngeal folds simply flop weakly and flaccidly. When an affected dog breathes in, the cartilages do not pull open—rather, they are sucked into the opening, or in severe cases sucked shut. Early in the condition, this creates increased noise when they breathe (called “stridor”); later, it can completely obstruct their airway, and they can suffocate.
The early signs of laryngeal paralysis can be quite subtle. They may be such things as a slight harshness in their panting. Very early there might be a simple voice change, usually a hoarse or raspy-sounding bark. Later, people report that they see their pet working harder to breathe, they have exercise intolerance and tire quickly, their facial expression is a bit anxious, and their chest is vigorously expanding. The pet may also look like he/she is “smiling” when they pant, with their lips pulled way back.
Because animals use their breathing as a means to cool themselves naturally, laryngeal paralysis patients are more prone to heatstroke under conditions that would not make a normal dog hot. This may be a simple walk outside on a sunny day or vigorous play on a cool day. When the paralysis is quite pronounced, it is very obvious that the animal is really working to breathe. The extra noise they create with each breath is harsh and easy to hear. Their tongue may be a darker red purple or blue. They are in “respiratory distress” and need medical assistance. Ironically, the airway compromise gets worse when they breathe harder, similar to asthma. Fast-moving air will suck the airway shut, while slow moving air will pass more easily. But the feeling of “air hunger” is a powerful drive, and will make an animal try to breathe harder. Additionally, some dogs will trigger their own crisis by simply barking. The vocal cords are in the larynx; when the dog tries to bark, they contract other neck muscles and narrow their airway and may incite a distress episode.
Medical care during a breathing crisis often entails oxygen therapy, external cooling, sedation to take the anxiety away, and possibly intubation and artificial respiration for a short period. Unfortunately, most patients that have reached a crisis point will continue to suffer these breathing episodes because their airway is ineffective.
“Can we treat this problem?”
After your veterinarian confirms that your pet has laryngeal paralysis (the vocal cords are observed under light sedation to monitor if they are moving correctly, and sometimes a drug is given to stimulate breathing to see if the folds move properly during the exam) then you and your veterinarian have to decide when and if to do surgery to “fix” the problem without causing worse problems. The reason they confirm the diagnosis is to make sure the pet doesn’t have a problem that similarly interferes with breathing such as collapsing trachea or a laryngeal or tracheal tumor.
Laryngeal paralysis is a problem of anatomy. The anatomy is interfering with the airflow necessary for breathing. Ironically, the larynx is also responsible for protecting the airway and lungs from fluids and food that should only go down the esophagus into the stomach. So, the correction is simply to move or remove the interfering anatomy without causing any new problems with airway protection.
|Image courtesy of the Animal Surgical Clinic of Seattle|
Many different approaches have been used to surgically treat laryngeal paralysis. Most veterinarians feel that out of the list of surgical procedures with good success and few complications, the Unilateral Cricoarytenoid Lateralization or “Tieback” is the best choice for most patients. Perhaps newer techniques will come along with better success in the future. To minimize the chance of fluids or food entering the airway, the surgeon will only pull open one side enough to prevent airway compromise and future breathing crises.
While any surgery can have some post-op complications, the biggest concern with this surgery is aspiration of regurgitated stomach contents into the lungs resulting in mild to severe pneumonia. Dogs with chronic vomiting or regurgitation issues (including dogs with megaesophagus) are not good surgical candidates for this procedure. There is a medication called Doxepin that can be tried to improve laryngeal motion if your pet is not a surgical candidate or if you choose not to pursue surgery. Ask your veterinarian if this might be an option for your pet.
While laryngeal paralysis and its post-operative complications can be quite severe, the majority of families living through this with their pets are happy with the quality of life that is restored with surgery. Restrictions following surgery are few; no neck collar/ leash indefinitely, minimize barking for 6 weeks, elevated feeding station indefinitely, and use of caution when swimming.
It is less and less common for aspiration pneumonia to be fatal, and patients can make a full recovery even in severe cases. The majority of patients do not suffer these complications and go on to live well with the ease of breathing restored. Good to excellent long term results are reported in 90-100% of patients. Complications (10-27%) include aspiration pneumonia (24- 25%) after excessive abduction; infection; and tearing of the tissues with subsequent laryngeal collapse. Voice change is common. Complications are less frequent with more experienced surgeons and with unilateral (versus bilateral) tieback procedure. Each patient must be considered individually though; talk through these potential complications with your veterinarian and choose the most appropriate plan for your pet. It is less and less common for aspiration pneumonia to be fatal, and patients can make a full recovery even in severe cases. The majority of patients do not suffer these complications and go on to live well with the ease of breathing restored. Good to excellent long term results are reported in 90-100% of patients. Complications (10-27%) include aspiration pneumonia (24- 25%) after excessive abduction; infection; and tearing of the tissues with subsequent laryngeal collapse. Voice change is common. Complications are less frequent with more experienced surgeons and with unilateral (versus bilateral) tieback procedure. Each patient must be considered individually though; talk through these potential complications with your veterinarian and choose the most appropriate plan for your pet.
BLOG WRITTEN BY:
Dr. Dana Lewis
Dr. Dana assists families with Pet Hospice and Euthanasia in the Raleigh North Carolina area (Raleigh, Durham, Chapel Hill and the greater Triangle, as well as Wake, Durham, Orange, and Chatham counties.)
Blog posted by:
Vet Mary Gardner
Vet Mary Gardner