WHAT IS IT?
The larynx is a rigid cartilage structure located in the throat at the upper end of the trachea, the tube that carries air from the mouth to the lungs. It contains the vocal folds that allow us to speak and dogs to bark. The upper end of the larynx has three structures, the arytenoid cartilages and the epiglottis, that prevent aspiration of food and fluids. During inspiration the arytenoid cartilages are retracted by the cricoarytenoideus dorsalis muscles. Paralysis of one or both of these muscles prevents the airway from opening fully.

WHAT ARE THE SIGNS?
Common signs are those of airway obstruction--roaring respiratory sounds, exercise intolerance, coughing, gagging and change in tone of voice. Overheating or heatstroke can occur from an inability to adequately ventilate through panting. Some dogs also show other neurological signs such as limb weakness or difficulty eating.

WHAT IS THE CAUSE?
There are genetic factors in some breeds, such as Labradors and Rottweilers, but in most cases the cause is unknown. Other commonly affected breeds are the St. Bernard, Irish setter and Afghan hound. Many laryngeal paralysis patients are also hypothyroid although the connection is not understood.

HOW IS IT DIAGNOSED?
The condition is diagnosed by direct visualization of the arytenoid cartilages by laryngoscopy with the patient under light anesthesia.

HOW IS IT TREATED?
There are a variety of surgical approaches but the best seems to be a technique called laryngeal tieback.