Juvenile Laryngeal Paralysis and Polyneuropathy
Juvenile Laryngeal Paralysis and Polyneuropathy (JLPP) is a neurological disorder which has been discovered in Black Russian Terriers. As a disorder affecting the nerves, it is named polyneuropathy: poly- (many), neuro- (nerves), -pathy (a disease). It is a most commong disorder in the Black Russian Terrier breed. The disorder appears too be similar to Charcot Marie Tooth disease which affects humans. The same as in Charcot Marie Tooth disease, Juvenile Laryngeal Paralysis and Polyneuropathy in dogs appears as very heterogeneous, from predominantly demyelinating forms to predominantly axonal forms. Predominantly demyelinating forms are characterized by very slow motor nerve conduction velocities (MNCV) and histopathological evidence of demyelination. Predominantly axonal forms are characterized by mildly slowed MNCV and axonal abnormalities on histopathology with many intermediate forms
The first symptoms of the disease appear in the larynx and throat. In a healthy dog, one of the longest nerves in the body supplies the muscles of the voice box, called larynx. While the dog is barking, air moves over the vocal folds, which start to vibrate. On the other hand, when the dog breathes in, larynx’s muscles pull the vocal folds on the side, so the air can easily enter the lungs. When the nerves are unable to transmit this message correctly, and the muscles become weak or even paralyzed. The dog is unable to breath in properly, due to vocal fold which cannot be pulled out of the way. This is called the laryngeal paralysis, and it is often the first symptom in the affected dogs. Affected dogs breath noisily, and the air flow into the lungs is particulary difficult during the dog’s exercise or in the hot weather. Choking the food or water is common, which often results in pneumonia. Abnormalities in the eye development of the affected dogs have been also reported. JLPP affecred dogs appear to have smaller eyes than normal, a condition called microphthalmia, and they develope cataracts as well as other changes.
Juvenile Laryngeal Paralysis and Polyneuropathy (JLPP) is caused by a mutation in the RAB3GAP1 gene. The disorder is inherited in an autosomal recessive manner. In case of showing the jlpp symptoms, the healthy parents of the affected cub are obligate heterozygotes, and therefore carry one mutant allele. Heterozygotes have no symptoms. At conception, each cub has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier. There is no cure for this disorder, and only way to prevent it, is to breed dogs which are not carriers of the mutation. Defected genes for autosomal recessive disease can be passed for many generations without affected individuals occurring until two carriers are bred to one another. The only way to find out if there is a chance of getting an affected puppy is to do genetic testing.
Mhlanga-Mutangadura, T., Johnson GS. (2016): A mutation in the Warburg syndrome gene, RAB3GAP1, causes a similar syndrome with polyneuropathy and neuronal vacuolation in Black Russian Terrier dogs. Neurobiol Dis. Feb;86:75-85.
Mhlanga-Mutangadura, T., Johnson, G. S., Johnson, G. C., Hansen, L., Tamassia, O’Brien, D. P., et al. (2014): The whole genome sequences from a Rottweiler and Black Russian Terrier with overlapping neurological syndromes contain the same RAB3GAP1 frame shift mutation.