A genetic variant in the RNF170 gene that causes NAD has been identified in the Miniature American Shepherd breed. The first clinical signs appear at around two years of age.

Affected dogs develop a slowly progressive weakness and coordination problems of the hind limbs up to bilateral incomplete paralysis. Slowly progressing signs of damage to the spinal cord in the thoracic and lumbar spine can be observed. The cervical spine, cerebellum or forebrain may also be affected. No pain or balance problems are observed in the affected dogs. The abnormalities in the gait pattern appear more pronounced when walking than when walking faster. The progressive symptoms lead to a reduced quality of life, but the life expectancy of affected dogs is not significantly shortened per se.