Polyneuropathy in the Alaskan Malamute

contributed by Vicky MacLean

Polyneuropathy means "many abnormalities of the nervous system". Early literature on the subject is by Dr. Lars Moe from Norway where numerous cases were diagnosed in first generation offspring of Alaskan Malamutes imported from the United States in the 1970's. Veterinary colleges in the U.S. have seen a number of cases since then, but I have been able to find no documented cases dating to before the Norwegian cases. I have, however, heard of several possible, but unconfirmed cases from that era.

The condition is generally characterized by a lack of coordination and instability that leads to a labored gait which has been described as a bunny hopping gait where the rear legs work together to prop up the dog rather than to propel him. The degree of affection may vary from mild to severe. The dog may fall down, walk on the tops of his feet (with the foot folded under itself) or his gait may just look a little off. Exercise intolerance, loss of muscle mass, changes in voice due to an affected larynx and problems swallowing and regurgitating have also been described. First indications of the problem may be subtle — a dog that no longer jumps up on his dog house, a dog that lies down to eat, a dog that no longer jumps up and down at feeding time or shows a slight tremor in his legs. It cannot be emphasized enough that symptoms may vary considerably from dog to dog.

Age of onset is in the older puppy or young adult. There is not enough data to say exactly what ages it may come on, but six months to two years seems to be a good ball park figure with most cases noticed at over a year of age. In the dogs we have seen, the onset is quite sudden rather than gradual and progressive. The symptoms may last for about six to eight months then abruptly lessen but not go away completely. Literature says that symptoms will again appear in the dog when he gets older. Several people have reported that their dog was always "uncoordinated", while our dogs ran on the team for a winter before showing any symptoms.

Because the disease is seemingly rare it may often be misdiagnosed or undiagnosed. There are also cases of some spinal problems (lesions or bone spurs) producing superficially similar symptoms but it would be extremely unlikely for bone spurs to cause absolutely symmetrical symptoms like this does. Because of this it is important to get a positive diagnosis from a school of veterinary medicine or a veterinary neurologist where they can run tests that your local vet cannot do. The diagnostic tests include nerve and muscle biopsies, electromyography and nerve conduction velocities. If the results are positive, these tests will show a deterioration of the myelin sheath of the nerve and conductivity may be slower than is normal. They may also do x-rays to see if there is an enlarged esophagus. Due to the late age of onset, test breeding to clear dogs is not practical as it is with dwarfism.

If we malamute breeders and owners are to put an end to this debilitating problem we must work to get positive diagnoses and start looking at what lines are producing the problem. Test breedings in Norway indicate that the disorder is probably a simple recessive like dwarfism in our breed, so if you have turned up a case, both parents would be carriers. Not facing up to the problem will only put us in worse shape a few years down the road.

To get a start on eliminating the problem we need to get positive diagnoses, pull parents of affected dogs from your breeding programs and likewise pull all offspring from those parents from breeding programs as they have a high probability of being carriers. This will go a long way in cutting down on the problem. This means you will need to stay in contact with puppy buyers or breeders of your dogs and let them know how important it is to work on this together. You will need to be honest and open up to other breeders, especially those working with dogs closely related to yours. Tests are expensive, but sometimes a teaching institution such as a school of veterinary medicine will do these tests for free or for a reduced rate to give their students experience. Veterinarians I know of that are interested in this problem include Dr. Mike Moore, a neurologist at Washington State University in Pullman, Washing and Dr. Kyle Braund at Auburn University in Alabama.

What next? The Alaskan Malamute Club of America genetics committee, funded by the Alaskan Malamute Research Foundation, has just finished an educational video titled "Inherited Polyneuropathy in the Alaskan Malamute" which will be available when a presentation on Malamute "coat funk" is added (hopefully by summer 1998). The genetics committee will also be looking into storing DNA samples bit by bit until there are enough positive cases and funding to do DNA research on the disorder.

Anyone who thinks they might have polyneuropathy in their dogs, or who just wants to talk about it, feel free to contact Vicky MacLean at 2065 Colorado Gulch, Helena, MT 59501, or call (406) 442-1918 or email agillabs@mcn.net.