A 2-month-old, orphaned Arabian filly, presented to Cornell's Equine Hospital on June 23, 2007 with an 8-day history of diarrhea and a 4-day history of abdominal distention and depression. No colostrum was given to the neonate at birth; the filly's diet consisted on milk replacer until weaning. Pertinent physical exam findings included depression, a thin body condition, abdominal distension with a palpable fluid wave, an enlarged clitoris, and fecal staining of the caudal hind limbs (diarrhea). The problems addressed were abdominal distention, diarrhea, depression, and clitoral enlargement. Top differentials to explain the physical exam findings included neoplasia, gastric ulceration, and parasitism. An exploratory celiotomy found an enlarged right ovary (25 x 15 x 10 cm) and a bilateral oophorectomy was performed. Histopathology definitively diagnosed the filly with a granulosa cell tumor of the right ovary.