Leukodystrophy

Patty Khuly

Summary

Leukodystrophies comprise a rare class of inherited nervous system diseases in which the protective covering of the peripheral nerves progressively loses an essential fatty protein called myelin. These so-called “demyelinating” diseases most often manifest as progressive weakness and difficulty walking––usually in young dogs, though cats have been known to be affected as well.

A wide variety of these diseases exists and most tend to be highly breed specific. One significant variation from most includes a leukodystrophy disease called globoid cell leukodystrophy. This version of leukodystrophy differs from the others in that the cause of the problem has been specifically identified as a disruption in myelin production due to the inherited deficiency of a certain enzyme.

For all kinds of leukodystrophies in which the mode of inheritance has been determined (including that of globoid cell leukodystrophy), the pattern has been identified as autosomal recessive.

Symptoms and Identification

These will vary according to the leukodystrophy variant and breed but can begin in dogs as early as two weeks of age and will progress slowly or rapidly from weakness to loss of coordination, abnormal gait and eventual paralysis in a great many cases. Again, however, the signs will vary according to the specific kind of leukodystrophy inherited.

Diagnosis of the condition is not straightforward given that the rarity of the disease renders its identification elusive. Normally, veterinary neurologists are enlisted to help with MRIs, nerve conduction studies and other helpful approaches to rule out diseases with similar symptoms. MRIs will be most helpful in determining whether the characteristic demyelination has taken place. Nerve sheath biopsy may also be helpful.

In the case of globoid cell leukodystrophy, a specific test is available to determine whether the disease has been inherited.

Affected Breeds

Treatment

There is no known treatment for this class of diseases.

Veterinary Cost

The cost of diagnosis can be significant given the need for expensive imaging equipment and the heavy reliance on neurologist consultation.

Prevention

Because most dogs inherit this condition as an autosomal recessive trait, all affected dogs and their first degree relatives must be removed from the breeding pool. For globoid cell leukodystrophy, blood testing will help identify not only affected dogs but the carrier state as well, thereby aiding breeders in weeding out this trait through appropriate breeding.

References

OFA

Ackerman, L. 1999. The Genetic Condition: A Guide to Health Problems in Purebred Dogs. pp 137-138. AAHA Press. Lakewood, Colorado.

LeCouteur, R.A., Child, G. 1995. Diseases of the spinal cord. In S.J. Ettinger and E.C. Feldman (eds.) Textbook of Veterinary Internal Medicine, p. 629-696. W.B. Saunders Co., Toronto.