Leukoencephalomyelopathy affects dogs and is an inherited progressive neurologic disease. This is a degenerative disorder of the central nervous system in the Leonberger dog breed. 

Affected dogs experience degeneration of a fatty tissue layer, known as Myelin, which forms an insulating sheath around nerves and increases the speed of nerve signal transmission.

Dogs with Leukoencephalomyeopathy present with slowly progressive signs of neurological dysfunction including incoordination, high stepping gait, and weakness in all four limbs, as early as one year of age.

A wide-based stance with occasional involuntary crossing of limbs is common. Inappropriate placement of feet while walking may result in severe toenail wear.

Affected dogs are often humanely euthanized by five years of age due to increasingly severe neurological dysfunction and a lack of effective treatment options.