Neurotoxicology
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Pyridoxine, a water-soluble vitamin, produces a sensory neuronopathy when administered in high doses to dogs. Beagles who received a daily oral dose of 300 mg/kg of pyridoxol hydrochloride developed a swaying gait within 9 days. They eventually became unable to walk, but were not weak. ⋯ Degeneration of sensory nerve fibers in peripheral nerves, dorsal columns of the spinal cord and the descending spinal tract of the trigeminal nerve was apparent. The pathogenesis of these changes is unclear, but may, in part, reflect the selective permeability of blood vessels in the peripheral ganglia. It is apparent that the peripheral neuropathy previously attributed to pyridoxine actually represents a toxic, peripheral sensory neuronopathy.