This section is on laryngeal paralysis. If you have any questions please feel free to email me.
The larynx is the structure in the body that is responsible for protecting the trachea (windpipe; the tube that connects the nose and mouth to the lungs) from the pathway to the esophagus (the tube that connects the mouth to the stomach). When an animal swallows, the larynx has several sturctures that come together to form a seal over the trachea. When the animal breathes, these structures move out of the way so that the pathway to the trachea is clear and air is free to move into and out of the lungs. In laryngeal paralysis, one or more of these structures (usually the vocal folds) becomes unable to move out of the way and as a result the flow of air is impeded. The severity of the condition is directly related to the size of the structure that is impeding air flow. Reduced air flow results in a decreased ability to bring oxygen into the body and a decreased ability to cool the body.
Laryngeal paralyis can be congenital (reported in Bouvier des Flandres and Siberian Husky breeds), as part of a generalized nerve disease like the Dalmatian gets, or acquired (idiopathic) in which giant and large breed dogs especially the retrievers are overrepresented. The idiopathic (no known cause) acquired form can be associated with hypothyroidism, neck trauma, nerve abnormalities, and lots of other diseases or associated with no other disease at all. No one knows why these associated primary conditions lead to laryngeal paralysis or even if they do although treating these primary diseases often corrects the paralysis. Typical age of occurrence is 9 to 12 years (can occur anytime in life though) and the Golden and Labrador Retrievers seem especially prone to developing the condition. Signs include change in the sound of the dog's bark, harsh breathing, exercise intolerance, fainting, collapse, and even sudden death. Mild cases can often be treated with management -- ie keep them cool and quiet. Moderate cases can be managed with rest and quiet until surgery can be performed to remove the obstructing tissue. Severe cases need emergency treatment including a tracheotomy (tube in the trachea to breathe through), oyxgen, intubation (tube through the larynx into the trachea to provide an open airway), and immediate surgery to correct the obstructive tissue. If the surgery is successful, prognosis for a normal length, good quality life is excellent. Prognosis declines as the repsonse to surgery worsens.