Nigropallidal encephalomalacia (original) (raw)

Nigropallidal encephalomalacia or Chewing disease is a neurological condition that affects horses that have eaten certain toxic plants. Affected animals are unable to prehend food because of lip and tongue paralysis, and may appear to keep their jaws open with the tongue protruded because of reduced jaw tone. Some horses may appear to show their upper teeth because of increased hypertonicity (increase muscle tone) of the facial and upper lip muscles. Other animals may show severe depression and carrying their heads low. Because poisoned horses are unable to eat, these animals become weakened and ultimately die of starvation.