Ask the Vet: Laryngeal paralysis and aging dogs

Owners of large breed dogs will often assume that mobility changes in their older companions are associated with arthritic changes that owners will incorrectly associate with hip dysplasia.

However, in some older dogs the weakness and difficulty rising can be a manifestation of a degenerative condition called Geriatric Onset Laryngeal Paralysis Polyneuropathy (GOLPP). The average age of onset is about eleven years old and it is most common in Labradors, but it can also be seen in Newfoundlands, German Shepherds, Brittany spaniels, and other large breeds.

Symptoms can vary from pet to pet, but generally start out as increased effort and noise when panting and some changes in walking with the back legs. The change in breathing is a result of one of the nerves to the larynx or voice box not functioning well, called laryngeal paralysis. The arytenoid cartilages which are the valves to the trachea that open and close do not open wide enough to allow normal airflow.

Often you may only notice a louder pant when it is hot or during and after exercise. Some dogs may develop a hoarse or throaty bark. With the doors to the trachea not functioning well some of these dogs will clear their throat or retch, especially after laying down for extended periods or eating and drinking. They can also lose some esophageal function from loss of nerve function to the smooth muscles, and they may have trouble swallowing or regurgitate food.

Originally laryngeal paralysis was thought to be a single disease entity, but recent studies have shown that many dogs also have other more widespread signs of neurologic dysfunction. Loss of muscle mass in the back legs will develop and subtle losses of coordination are early signs. You may notice the nails on the back feet scuffing the pavement or maybe a wobble called ataxia when walking.

This can progress to difficulty getting up or more profound stumbling. Historically this was the assumption of arthritic changes since it affects breeds that are overrepresented with orthopedic disease as well. This loss of muscle mass and strength in the back legs can compound the exercise intolerance from the inability to pant or breathe as well from the laryngeal paralysis and some of these dogs may collapse during rigorous exercise.

To diagnose GOLPP your veterinarian may need to run some tests to establish the paralysis of the arytenoids and rule out other conditions that can mimic this disease, but no single test exists for GOLPP. These pets can frequently have concurrent orthopedic disease, so do not assume that all the symptoms are attributable solely to neurologic deterioration. The good news is that GOLPP is not painful and in most pets the nervous degeneration is slowly progressive over many years.

If your pet’s breathing is severely affected surgery to “tie back” the arytenoid cartilage can be performed to help open the airway and make it easier to breathe, but there is no treatment for the neurologic deterioration in the rest of the body. Lifestyle changes to avoid exercise during hot weather and occasionally adjusting feeding habits if the esophageal function is impaired can avoid more serious complications from the disease.

Having had a dog with the disease and diagnosed it in many others, it is a relief to know why your aging pet has changed and a comfort that this is not painful since often it is assumed from the symptoms that arthritic changes are the cause. Michigan State University’s college of veterinary medicine has led the research on this disease and has a highly informative website if you would like to learn more ( www.cvm.msu.edu ).