The prognosis for horses with equine motor neuron disease (EMND) caused by prolonged vitamin E deficiency is usually poor, but veterinarians from the University of Minnesota showed that early diagnosis and treatment can help these animals.

Equine motor neuron disease is usually diagnosed too late for the veterinarian to help the animal, said Holly E. Bedford, DVM, MS, who presented the data at the recent 2010 ACVIM (American College of Veterinary Internal Medicine) Forum held in Anaheim, Calif. Classic clinical signs of EMND include weight loss (even though the horse's appetite is normal), muscle atrophy (wasting), weakness and twitching, an elevated tail head, increased periods of recumbency (inability to stand), a camped-under stance, and occasionally black discoloration of the incisors and a pigmented retinopathy (non-inflammatory damage to the retina).

"Often, the common complaint by the owner is weight loss or decrease in performance," she said. "Often the owners interpret the muscle atrophy as weight loss."

Veterinarians base a diagnosis of EMND on finding significant muscle atrophy that affects the nervous system on a biopsy of the sacrocaudalis muscle, which is located above the tail head on either side of the spine along with low levels of vitamin E on a blood test. But Bedford said she and her colleagues would have missed 40% of their cases if they used these standard diagnostic criteria