Enteric dysganglionosis resembling intestinal neuronal dysplasia in a foal with bacterial colitis.

A 5-day-old quarter horse colt with a history of hypothermia, agonal breathing, and diarrhea was euthanized. At necropsy, numerous slightly raised, discrete, closely approximated submucosal nodules were observed in the colon and small intestine. Histologically, these nodules were composed of expanded submucosal mesenchyme that contained numerous neurons either individually or in ganglia. Thirty-two percent of these ganglia included 8 or more neurons, in contrast to 6% in an age-matched foal. Some nodules had necrosuppurative inflammation with vasculitis, thrombosis, and bacterial colonization. A few heterotopic neurons were randomly distributed in the mucosa and the muscularis mucosa. Histologic changes were most consistent with intestinal neuronal dysplasia, a disease of the submucosal plexus described in humans.