Neuroaxonal dystrophy, or NAD, is a neurologic disease that can affect horses as well as humans, sheep, cats, and dogs. The condition is not yet fully understood, although researchers believe there might be a genetic component. At the 2010 American Association of Equine Practitioners convention, held Dec. 4-8 in Baltimore, Md., one presenter discussed findings in a series of cases in Quarter Horses at a single cutting horse breeding farm.

"Neuroaxonal dystrophy is a degenerative disease of selected neurons and their axonal processes in the nervous system," explained Carrie Finno, DVM, Dipl. ACVIM, a graduate student at the University of California, Davis (UC Davis). Clinical signs of the disease include:

• Symmetric ataxia (incoordination) that can appear much like wobbler syndrome,

• A base-wide stance at rest,

• Abnormal circling,

• Dull mentation,

• Often laterally odd foot placement (inappropriate proprioception, or the horse not knowing where his feet are),

• Toe stabbing when walking up inclines,

• Weakness behind when going downhill, and

• Trouble walking over curbs (such as those in parking areas/on road edges).

Mild cases can present with performance issues, said corresponding author John Madigan, DVM, MS, Dipl. ACVIM, a professor of veterinary medicine at UC Davis.

"This disease is clinically indistinguishable from equine degenerative myeloencephalopathy," Finno noted. "The lesions (in the nervous system) are the same, just distributed differently. The disease should be referred to as NAD/EDM to encompass the full extent of the lesions