[A horse with grass sickness].

A three year old warm-blood gelding with severe colic was referred to a veterinary clinic. The history revealed that the horse was found early in the morning with severe colic, and laying in the pasture. On arrival the clinical examination showed a complete wet horse with a pulse rate of 92/min, a respiratory rate of 24/min., a pcv of 0.50 L.L.-1, a T. of 38.0 degrees C, and no gastric reflux. Rectal examination revealed a sticky rectal mucous membrane and a colonic impaction together with displacement of the large colon. A diagnostic laparotomy showed an impaction as is seen in horses with Grass sickness. After euthanasia the coeliac ganglion was removed and histology showed dystrophy and chromatolysis, degenerative changes found in horses with Grass sickness.