Unusual ovarian activity in a mare preceding the development of an ovarian granulosa cell tumour

An 8-year-old mare, with a foal at foot, was inseminated on foal heat with frozen semen, with the resultant pregnancy lost between days 34 and 41. The right ovary developed a large anovulatory follicle that was non-responsive to multiple doses of ovulating agents. The follicle eventually appeared to luteinise, although plasma progesterone concentrations did not reflect this. Another follicle developed, responded to GnRH and resulted in a pregnancy from frozen semen that went to term with a healthy foal. When the mare was examined after foaling, the structure on the right ovary appeared to be a granulosa cell tumour; the left ovary was smaller than normal and non-functional. Surgical removal of the right ovary before increasing photoperiod resulted in a return to function of the left ovary and a pregnancy to frozen semen on the second cycle following removal. Figures showing concentrations of inhibin, progesterone, androstenedione, oestradiol and testosterone are presented for this entire period. Unusual ovarian activity in the mare might be a prelude to the development of a granulosa cell tumour.     

Udder development, lactation and ascites in a ewe with an ovarian granulosa cell tumour

A 20-month-old sexually intact female mixed breed sheep was examined for lameness, unexpected udder development, lactation and anorexia. Tachycardia, tachypnoea, severe abdominal distension and vaginal prolapse were evident upon physical examination. A right hindlimb lameness was present at the walk. The udder was well-developed and milk, normal in appearance, was easily expressed from each teat. Ultrasonographic evaluation revealed a non-pregnant uterus, severe ascites and a large (12 cm diameter) abdominal mass. Although surgical treatment was discussed, the owners elected to euthanase the ewe. Necropsy examination confirmed the presence of severe ascites due to a ruptured ovarian tumour. The tumour was characterised as a granulosa cell tumour histologically. Unexpected udder development and lactation presumably occurred secondary to oestrogen and progesterone production by the tumour. To the authors' knowledge, this is the first report of udder development, lactation and ascites in a ewe secondary to an ovarian granulosa cell tumour.     

Metastatic granulosa cell tumor in a mare.

A 5-year-old Quarter Horse mare was referred for evaluation of an acute non-weightbearing lameness of the left hind limb in which musculoskeletal abnormalities had not been detected. After admission, the mare had signs of colic. Exploratory laparotomy revealed the left ovary to be large, masses in the left sublumbar space, and diffuse infiltration of the mesentery, omentum, liver, and spleen with variably-sized masses. The mare was euthanatized, and granulosa cell tumor was identified on histologic examination of the left ovary, left sublumbar and cranial thoracic lymph nodes, omentum, mesentery, liver, spleen, and lung.     

Small-colon rupture attributable to granulosa cell tumor in a mare

A large granulosa cell tumor was believed to be responsible for causing obstruction and subsequent rupture of the small colon in a 10-year-old Quarter Horse mare. Two months earlier, a mass, tentatively diagnosed as granulosa cell tumor of the left ovary, had been identified by means of rectal palpation and ultrasonography. The mare was evaluated for clinical signs of acute, severe, abdominal pain, increased heart rate, cyanotic mucous membranes, clinical dehydration, with high PCV, leukopenia, and extreme abdominal distension. A large soft tissue mass and taut band that constricted the lumen of the small colon were palpable per rectum. Septic peritonitis was diagnosed on the basis of results of abdominocentesis. Exploratory surgery revealed extensive fecal contamination of the abdominal viscera, and the mare was euthanatized because of the resultant poor prognosis. At necropsy, the small colon was occluded by a taut, left broad ligament and the ovarian mass that was proved to be a granulosa cell tumor. The occlusion had caused impaction of the small colon, with subsequent perforation at the level of the broad ligament.     

Diabetes mellitus associated with bilateral granulosa cell tumors in a mare

Both ovaries in a 10-year-old American Saddle Horse mare were determined to be larger than normal. The mare had problems with infertility during the preceding 3 years. Clinical evaluation revealed that the mare was polyuric, polydypsic, hyperinsulinemic, and hyperglycemic, and had reduced tolerance to exogenous glucose. Bilateral granulosa cell tumors were identified on histologic examination of the ovaries. The precise mechanism for the secondary diabetes mellitus was not determined; however, the cause was suspected to be a result of the synthesis and release of a hormonal substance by the tumor that affected carbohydrate metabolism and resulted in decreased peripheral sensitivity to insulin.     

Granulosa thecal cell tumour in a mare causing hypertrophic osteopathy

Hypertrophic osteopathy (HO) is a rare condition in the horse characterised by symmetrical proliferation of connective tissue and subperiosteal bone, along the diaphyses of limb bones. In this case, a 10‐year‐old Irish Draught cross Thoroughbred mare was presented for investigation of weight loss, lethargy and firm swelling of all 4 distal limbs. Radiographs of the distal limbs revealed palisade‐like periosteal new bone formation perpendicular to the cortex of the distal third metacarpal and metatarsal bones, proximal (P1) and mid (P2) phalanges. Rectal examination revealed a mass of approximately 20 x 30 cm in the right caudoventral abdomen. The mare was diagnosed with HO due to a granulosa thecal cell (GTC) tumour. The GTC tumour was removed and the diagnosis confirmed on histological examination. Clinical examination and radiographs of the distal limbs after surgery demonstrated reduction in size of the limb swellings and new bone formation. To the authors' knowledge this is the first report of HO due to a GTC tumour in a mare.     

Haemoperitoneum in a pregnant mare with an ovarian haematoma

Haemoperitoneum is a rarely reported but life‐threatening complication of a multitude of disease processes that can affect horses. This report describes an unusual case of haemoperitoneum in a pregnant mare attributed to a unilateral ovarian haematoma during early gestation. The mare was treated with supportive care and discharged 8 days after initial presentation. Following discharge, the mare maintained her pregnancy to term and delivered a live colt at 321 days of gestation.     

Granulosa cell tumour: An interesting case in a pregnant mare

This report describes the successful management of a pregnant 14‐year‐old seven‐eighths Thoroughbred mare with an ovarian granulosa cell tumour. The mare initially presented with unilateral ovarian enlargement whilst being managed for artificial insemination, demonstrating normal ovarian function with ovulation from the contralateral ovary leading to conception. The mare subsequently re‐presented with stallion‐like behaviour at 3.5 months gestation and ovarian suppression was evident. The mare maintained her pregnancy and delivered a live colt foal at term. Ovariectomy was performed 3 months post foaling and the mare regained cyclic activity 9 months post surgery. The mare then conceived and became pregnant once more. The diagnostic and therapeutic challenges during pregnancy are discussed.     

FSH and LH concentrations preceding post-partum ovulation in the mare

Equine follicle stimulating hormone (FSH) and luteinizing hormone (LH) were measured in the serum obtained from pregnant mares, bled daily, from up to 17 days before parturition until the first ovulation after parturition. LH was at baseline levels until 2 days before ovulation when it started, and continued, to rise until after ovulation. FSH surges occurred at approximately 24 and 14 days before this post-partum ovulation (12 and 2 days before parturition), thus showing a similar pattern to the cyclic mare, consistent with the hypothesis that 2 surges at these times prepare and prime follicles for subsequent ovulation. The high plasma oestradiol levels that occurred during and immediately before these FSH surges did not show a negative feedback, or the inverse relationship between FSH and oestradiol which occurs in the cyclic mare, and in other species.     

Review of seven cases of granulosa cell tumour of the equine ovary

This paper reviews the equine granulosa cell tumour (GCT) and describes the clinicopathological features, treatment and outcome in seven cases of GCT in mares. Mares were presented with unilateral ovarian enlargement during the 2007 to 2010 breeding seasons. The mean (sd) age of the mares was 11.7 (5.96) years. Three mares were multiparous barren, three were nulliparous and one was primigravida. Behaviour at presentation was 57 per cent anoestrus, 28 per cent with stallion-like behaviour and 14 per cent with persistent oestrus. All mares had unilateral ovarian enlargement. Six non-pregnant mares had a small and inactive contralateral ovary; the pregnant mare had a single small corpus luteum on the contralateral ovary and was at three-and-a-half months' gestation. Enlarged ovaries measured 7 cm to an estimated 30 cm in diameter. 28 per cent had a multicystic ultrasound appearance, 57 per cent were dense structures and 14 per cent were of mixed appearance. Mean concentrations of progesterone were <1 ng/ml, oestrone sulphate 3.06 (2.32) ng/ml and testosterone 0.58 (0.64) nmol/l in non-pregnant mares. Inhibin was elevated in all non-pregnant cases at 7.6 (12.45) ng/ml. The pregnant mare had concentrations of progesterone 2.5 ng/ml, oestrone sulphate 81.0 ng/ml, testosterone 1.9 nmol/l and inhibin 1.31 ng/ml. Mares demonstrating stallion-like behaviour had a significantly higher (P<0.001) testosterone concentration (1.85 [0.07] nmol/l) than those that did not (0.34 [0.26] nmol/l). Three mares underwent unilateral ovariectomy and resumed cyclic ovarian activity within nine months of surgery.     

Spontaneous repair of the atrophic contralateral ovary without ovariectomy in the case of a granulosa theca cell tumor (GTCT) affected mare

A 21 year old thoroughbred mare with granulosa theca cell tumor (GTCT) in the right side and atrophic contralateral ovary was investigated in this study. After arrival at our laboratory on 10th December 1999, the clinical diagnosis of GTCT was examined by rectal palpation and ultrasonographic image of ovaries. Plasma from peripheral blood was collected in the breeding and non-breeding seasons for hormonal analysis. The results showed that the contralateral ovary regained normal activity without any treatment of the GTCT affected ovary and contained follicles showing different sizes 19 months later. However, the affected right ovary, which became smaller after 4 months, was totally inactive without any follicle. The observations clearly demonstrate that without any treatment of the GTCT affected ovary, a mare can return to her normal estrous cycle within a certain period in some GTCT cases.     

Bilateral occurrence of granulosa-theca cell tumors in an Arabian mare

An Arabian mare was referred for right granulosa-theca cell tumor (GTCT) evaluation. The mare was presented 4.5 years later for a left GTCT, after successfully conceiving and delivering a normal foal in the interim. The concurrent or nonconcurrent occurrence of bilateral GTCT in mares appears to be rare.     

Immunohistochemical diagnosis of canine ovarian epithelial and granulosa cell tumors.

In humans and canines, the morphology of granulosa cell tumors is extremely variable and causes diagnostic difficulties. In human pathology, immunohistochemistry has been widely used for the diagnosis of granulosa cell tumors, whereas, limited studies are present in canine species. The aim of this study was to investigate the expression of cytokeratins, vimentin, and inhibin-alpha in canine normal ovaries, epithelial ovarian tumors, and granulosa cell tumors to establish an immunohistochemical panel for the differential diagnosis of ovarian tumors. Formalin-fixed, paraffin-embedded tissue sections from 4 normal ovaries, 8 granulosa cell tumors, and 6 epithelial ovarian tumors (2 adenomas and 4 adenocarcinomas) sections were obtained and stained with hematoxylin and eosin and immunohistochemically for cytokeratin AE1/AE3, cytokeratin 7, vimentin, and inhibin-alpha. In normal ovaries, cytokeratin 7, cytokeratin AE1/AE3, and vimentin were expressed in the surface epithelium. Granulosa cells were negative for cytokeratin 7 and displayed variable expression of vimentin, cytokeratin AE1/AE3, and inhibin-alpha toward follicular maturation. Granulosa cell tumors were negative for cytokeratin 7 and positive for inhibin-alpha. Conversely, ovarian epithelial cells tumors were positive for cytokeratin 7 and negative for inhibin-alpha. Both granulosa and epithelial cell tumors displayed variable expression of vimentin. Cytokeratin AE1/AE3 was expressed by all epithelial-derived tumors and 6 of 8 granulosa cell tumors. The results of this study suggest that useful immunohistochemical markers to distinguish epithelial ovarian tumors from granulosa cell tumors are cytokeratin 7 and inhibin-alpha.