Monitoring return to cyclicity following removal of a granulosa cell tumor associated with precocious lactation in an 11-month-old Holstein heifer

Abstract

An 11-month-old Holstein heifer was presented to the Western College of Veterinary Medicine for evaluation of precocious lactation associated with a palpably enlarged right ovary. Ultrasound examination of the ovaries revealed a 6 inch (15 cm) diameter right ovary with a multilobulated appearance, and a small left ovary measuring 0.6 inches (1.6 cm) long by 0.3 inches (0.8 cm) wide. The mammary secretion was consistent with milk: fat-3.07%, protein-4.78%, and lactose-1.07% with a somatic cell count of 4.8?106/mL. Prior to removal of the right ovary by right flank laparotomy, serum hormone levels were measured: testosterone (0.01 ng/mL), estradiol-17? (9.1 pg/mL), progesterone (0.2 ng/mL), prolactin (5.8 ng/mL), luteinizing hormone (0.14 ng/mL) and follicle stimulating hormone (0.32 ng/mL). Gross examination revealed that the right ovary weighed 7.34 oz (208 g) and was composed of numerous cysts (0.2-1.6 inches [0.5-4 cm] in diameter) containing fluid or blood. Microscopically, foci of cells of a follicular or luteal nature were noted. The definitive diagnosis was a right ovarian granulosa cell tumor, and milk secretion declined rapidly following tumor removal. The left ovary was monitored ultrasonographically at weekly intervals to determine onset of cyclicity. Follicular activity resumed between three and four weeks post-surgery, followed by detection of a corpus luteum at day 32. The heifer became pregnant five months post-surgery, and has since delivered a live calf. This case represents only the second reported case of precocious lactation associated with a granulosa cell tumor, and suggests that cyclicity is likely to return to the contralateral ovary less than a month after tumor removal.