A 3.5-year-old miniature horse gelding was evaluated for signs of colic and decreased faecal production. Initial clinical pathology showed severe hypoproteinaemia with an albumin concentration <10 g/l. Abdominal ultrasound identified multiple loops of small intestine with significantly increased wall thickness. Diagnosis of equine proliferative enteropathy was based on clinical and laboratory findings, as well as a positive faecal polymerase chain reaction and positive antibody titre (>1:240) to Lawsonia intracellularis. Treatment with intravenous oxytetracylcine and additional supportive care gradually resolved the clinical and laboratory abnormalities.