Retinal degeneration associated with vitamin E deficiency in hunting dogs.

A group of Walker Hounds and Beagles that were fed a diet of table scraps were examined because of slow, progressive loss of vision. Clinical and microscopic features of the disease were correlated to the dogs' micronutrient status. Sensory retinal degeneration, predominantly in the central tapetal fundus, was found in all dogs, and severity of changes varied with age of the dog. Plasma, serum, and tissue concentrations of vitamin E were low in affected dogs (10 to 40% of control values). Lipofuscin accumulation was found on microscopic examination in retinal pigment epithelium, smooth muscle cells of the intestinal tract, and neurons of the CNS. Findings were consistent with nutritional vitamin E deficiency and oxidative injury to photoreceptors of the retina. Changes in these dogs were similar to those described for central progressive retinal atrophy and equine lower motor neuron disease, suggesting these diseases may share a common pathogenesis to vitamin E deficiency.