What is Juvenile Laryngeal Paralysis & Polyneuropathy?
The brain controls muscles via signals that travel through nerves. A disease that affects the nerves is called a polyneuropathy: poly- (many), neuro- (nerves), -pathy (a disease). Due to a quirk in the way an embryo develops, one of the longest nerves in the body supplies the muscles of the voice box (larynx). The vocal folds vibrate as air moves over them allowing a dog to bark. When the dog breathes in, muscles in the larynx pull the vocal folds aside so that air can move easily into their lungs. These nerves also help to close the larynx when the dog swallows so they do not choke on their food.
If nerves are unable to convey messages properly, the muscles become weak or paralyzed. The longest nerves are often affected first; hence laryngeal paralysis is the first symptom. The vocal folds cannot be pulled out of the way as the dog breaths in. They vibrate noisily and can obstruct the flow of air into the lungs particularly when the dog is exercised or hot. The dog may also choke on their food or water or regurgitate, which can result in pneumonia.
The next longest nerves in the body go to the back legs, thus they are often affected next. The dogs have difficulty getting up and wobble as they walk. Eventually the front legs will also be affected. The symptoms do not occur until after weaning age, and thus the disease is called juvenile laryngeal paralysis/polyneuropathy or JLPP for short