Affected dogs generally present clinical signs of disease in adulthood (at least 8 years of age) with gradual muscle wasting and loss of coordination that generally begins in the hind limbs. The progression of the disease continues until the dog cannot walk. Small breed dogs tend to progress more slowly. In the late stages of the disease, dogs may develop incontinence and the front limbs may be affected. Affected dogs may completely lose the ability to walk from 6 months to 2 years after the onset of signs.