Nutritional Disorders of the Peripheral Nerve and Neuromuscular Junction
Pantothenic acid deficiency may develop in animals (particularly pigs) on rations of corn. Clinical signs include pelvic limb ataxia and a “goose-stepping” gait in which the stifles remain extended and the hips flex to lift the limbs off the ground. Pathologic findings consist of degeneration of myelinated fibers in peripheral nerves and chromatolysis and loss of sensory neurons in spinal ganglia.
Riboflavin deficiency (curled toe paralysis, see Riboflavin Deficiency) can develop if feed is not formulated properly. Affected chicks show poor growth, diarrhea, and weakness. There is inability to extend the hocks and progressive inward curling of the toes, so that chicks rest and walk on their hocks. Mortality is high by the third week. At necropsy the peripheral nerves, especially the sciatic nerves, are swollen. Histopathologically, there is hypertrophy of Schwann cells, demyelination, and minimal axonal degeneration. Chickens often recover with riboflavin supplementation unless the curled-toe deformity is longstanding.