Neuroaxonal dystrophy associated with vitamin E deficiency in two Haflinger horses.

Neuroaxonal dystrophy and minimal diffuse degenerative myelopathy was diagnosed in two female full sibling, 1- and 2-year-old, Haflinger horses. Both animals developed slowly progressive ataxia from the age of 4 months. Clinical signs, which were more prominent in the hind legs, included hypermetria and dysmetria. Histological examination revealed neuroaxonal dystrophy characterized by spheroid formation, vacuolation, astrogliosis and lipofuscin pigment deposition in macrophages and neuronal perikarya. These changes were restricted to the gracilis and cuneate nuclei, nucleus of the solitary tract, nucleus intermediomedialis in the sacral and the seventh segment of the cervical spinal cord and Stilling-Clarke's column in both horses and the medial vestibular nucleus in the older horse. Both diseased Haflingers had significantly reduced serum alpha- and gamma-tocopherol values. No significant alteration in serum total lipid concentrations and serum selenium values were observed. It is likely that the condition has a familial hereditary basis. It is unclear whether there is a link between the observed neuroaxonal dystrophy and vitamin E deficiency and further investigations are warranted.