A 7-month-old 41-kg (90-lb) American Miniature Horse gelding was admitted to a large animal referral hospital for evaluation of acute colic. The weanling had inappetence and was found recumbent 2 hours earlier in a field. The weanling received xylazine (1 mg/kg [0.45 mg/lb], IV) before transport to the hospital.
At the time of admission, the weanling was quiet, alert, and responsive and had no signs of colic. The patient was in good body condition but the abdomen had a distended appearance with a loss of concavity in the paralumbar fossa. The heart rate was 52 beats/min, consistent with mild