Granulosa cell tumours in the mare: A review of 52 cases

Abnormal mare behaviour is rarely associated with changes in hormonal markers of granulosa cell tumours: A retrospective study

BACKGROUND

Abnormal or undesired mare behaviours are often assumed to be associated with ovarian abnormalities.

OBJECTIVES

We aimed to determine the incidence of abnormal behaviours and their association with concentrations of one or more ovarian hormones associated with a granulosa cell tumour (GCT).

STUDY DESIGN

Retrospective descriptive.

METHODS

A total of 2914 hormonal profile samples submitted with the words behave, behaviour, or behaving in the submission history were analysed. The association between reported abnormal behaviours and concentrations of testosterone, anti-Müllerian hormone (AMH), inhibins and inhibin-B were assessed. Statistical analysis was performed using a Chi-squared test of association.

RESULTS

Of the 2914 cases that were submitted due to behaviour issues, 2506 (86%) did not have any of the measured hormones reach GCT-like concentrations. The remaining 408 cases had either one (63%), two (25.5%), or three (11.5%) hormones with concentrations consistent with those from confirmed GCT cases. Testosterone had the lowest percent of GCT-like values among the cases (7.7%), compared with AMH (9.4%), inhibins (9.6%) and inhibin B (8.7%). Stallion-like behaviour was significantly associated with increased concentrations of all four hormones. In contrast, aggression, oestrous and other abnormal behaviours were significantly less likely to be associated with increased concentrations of the hormones.

MAIN LIMITATIONS

Retrospective study, using sample submission history.

CONCLUSION

Overall, the abnormal behaviours among mares, except the stallion-like behaviour, were not associated with increased ovarian hormones. These results highlight the common misassumption about the involvement of the ovaries in 'abnormal behaviours' or 'undesirable behaviours' of mares.

Behavioral Disorders in Mares with Ovarian Disorders, Outcome after Laparoscopic Ovariectomy: A Case Series

Owner complaints of estrus-related behavior in mares are a common cause of referral for laparoscopic ovariectomy. Granulosa cell tumors are a common neoplastic condition affecting the equine ovary, causing behavioral changes at rest and reduced performance. The reported success rate of ovariectomy in treating behavioral disorders is 64-86%. The aim of this study was to retrospectively evaluate the long-term follow-up of laparoscopic ovariectomy in mares in our case series, focusing on the owner's perspective of the behavior of the mares after surgery. In addition, the histopathological features of the removed ovaries were investigated. The clinical records of mares that underwent laparoscopic ovariectomy between 2015 and 2022 were retrospectively reviewed. Owners complaining of poor behavior were interviewed about the main behavioral problem leading to referral and its eventual resolution after surgery. Eleven mares were included. The most common complaints were increased sensitivity on both flanks (10/11, 91%) and general riding problems (9/11, 82%). In 5/11 cases (45%), both ovaries were removed by laparoscopic ovariectomy. Histopathologic findings consistent with GCT/GTCT were found in five out of six examined ovaries (five granulosa theca cell tumors, GTCT). According to owner interviews, the scores assigned to each behavior improved significantly after surgery, regardless of histological findings. Although many factors can influence the behavior of horses, granulosa cell tumors (GCTs) proved to be a common cause and, as reported by the owners, ovariectomy resulted in improvement or complete resolution of the abnormal behavior.

Immunohistochemical markers for equine granulosa cell tumors: a pilot study

Sex cord-stromal tumors (SCSTs), generally referred to as granulosa cell tumors (GCTs) or granulosa-theca cell tumors (GTCTs) in equids, show complex compositions and variable numbers of hormone-producing cells. These tumors can be difficult to diagnose, especially in early stages. Therefore, we tested a panel of antibodies for vimentin, smooth muscle actin, laminin, Ki-67, E-cadherin, calretinin, moesin, p-ezrin, AMH, and aromatase, markers used for tumor composition and classification, progression, and prognosis in human SCSTs, on an exemplary grapefruit-size equine GCT within the left ovary of a 13-year-old mare with stallion-like behavior and elevated testosterone levels in comparison with normal ovarian tissue. The tumor showed a low proliferation rate and prominent moesin and p-ezrin staining in granulosa cells. E-cadherin, calretinin, aromatase, and AMH are suggested to be potential markers for different cell components of equine SCSTs that can support tumor diagnosis and classification.

Recurrent Colic: Diagnosis, Management, and Expectations

Most recurrent episodes of non-specific colic are self-limiting, and the results of clinical examinations are unremarkable. Differentiating these cases from serious diseases can be difficult, but repeated evaluations are warranted. Horses presenting with very frequent bouts of colic are more likely to have serious diseases and a higher mortality rate compared to horses presenting with less frequent bouts of transient colic. Horses with recurrent bouts of prolonged colic are more likely to have motility issues or partial intestinal obstruction. Non-gastrointestinal diseases can also cause recurrent bouts of pain ("false colic"). Adhesions are common causes of colic following abdominal surgery.

Granulosa cell tumour in a llama (Lama glama)

Hormonally active tumours are characterized by production and secretion of hormones, irrespective of endogenous feedback mechanisms. An adult llama had exuberant oestrous behaviour, infertility, elevated concentrations of oestradiol and a large ovarian mass. Necropsy revealed the presence of two large abdominal masses, one effacing the right ovary and one in the mesocolon. Considering the clinical and histopathological findings, we conclude that the llama was affected by a granulosa cell tumour. The case suggests that granulosa cell tumours in camelids are hormonally active, and the clinical presentation resembles that of other large animal species. To our knowledge, this is the first case report of an oestrogen-producing, metastatic granulosa cell tumour in a llama.

Markers for internal neoplasia in the horse

The diagnosis of internal neoplasia in horses is challenging. Increased production of hormones physiologic for adult animals (e.g., adrenocorticotropin, norepinephrine, and erythropoietin) or typical for the foetal phase (alpha-fetoprotein, anti-Müllerian hormone, and parathyroid-hormone-related protein) might aid in tumour diagnostics. Thymidine kinase-1 and alkaline phosphatase are examples of intracellular enzymes, whose activity in the blood may increase in some neoplasia cases. Furthermore, inappropriate production of abnormal monoclonal or autologous antibodies can accompany lymphoma and multiple myeloma. Many of those tumour markers lead to clinical or laboratory changes, called paraneoplastic syndromes, such as hypercalcaemia and erythrocytosis. The interpretation of the results of the tumour marker measurements in horses is complicated due to many factors affecting the markers' concentration or activity (e.g., young age, pregnancy, and inflammation) and other diseases triggering the same changes. Moreover, the presence of paraneoplastic syndromes is inconsistent, which leads to low sensitivity of those substances as tumour markers. In conclusion, screening for neoplasia in horses is not recommended. The measurement of tumour markers should be performed only in risk groups with suspicious clinical or laboratory findings, and the results should be interpreted with caution. It is advisable to add inflammatory markers to the tumour profile or repeat the measurements.

Equine granulosa cell tumours among other ovarian conditions: Diagnostic challenges

BACKGROUND

Granulosa cell tumours (GCT) are the most common ovarian tumours in mares. While the classical presentation may not represent diagnostic challenges, diagnosis is not easy in the early stages.

OBJECTIVES

Illustrate the variability in the presentation and serum biomarkers associated with ovarian abnormalities in the mare.

STUDY DESIGN

Retrospective case series.

METHODS

Nonclassical cases of GCTs and other ovarian conditions were identified and behaviour, GCT endocrine results, palpation and ultrasonographic findings are described and the diagnostic value of each is discussed.

RESULTS

Mares in this case series with GCTs had been presenting clinical signs ranging from no behavioural changes to behaviours including aggression, stallion-like and inability to work under saddle. Hormonal profiles of endocrinologically functional GCTs can be erratic and unpredictable. The clinical form and ultrasonographic appearance may also vary with time from an initially enlarged/anovulatory follicular structure that later develops a multicystic 'honeycomb' appearance. Mares with GCTs can also present with persistent anovulatory follicles or apparent luteal tissue that are unresponsive to treatment. If both ovaries are of relatively normal size and symmetry, but hormonal biomarkers are markedly increased (AMH >10 ng/mL, inhibin B and/or testosterone >100 pg/mL; 0.37 nmol/L), it is likely that a functional GCT is present. Still, it can be a challenge to decide which ovary to remove. Post-surgical endocrine testing can be helpful, especially if histopathology is not performed or a GCT is not found.

MAIN LIMITATIONS

Cases limited to 14.

CONCLUSIONS

Granulosa cell tumours present with a wide variety of clinical signs that do not fit what is commonly described as 'classic'. Only if AMH, testosterone and inhibin B concentrations are markedly increased, and there is an abnormally enlarged ovary, the diagnosis of a GCT is more confident. In the presence of normal size ovaries, normal hormonal biomarkers and abnormal behaviour, it is more likely that the ovaries are not involved.

Moody Mares-Is Ovariectomy a Solution?

Simple Summary

Unwanted behaviour in mares is a commonly presenting problem to the veterinarian. This behaviour may range from the mare being uncooperative or aggressive when handled on the ground, kicking, bucking or rearing when ridden or being aggressive towards other horses. In some cases, ovarian neoplasms (cancers) cause the mare to change behaviour, but in other cases, there is no apparent reason for the unwanted behaviour. The aim of the present study was to evaluate whether ovarian removal in mares with unexplained unwanted behaviour improved the mare’s behaviour or rideability from the owner’s perspective. Twenty-eight mares underwent surgical ovarian removal. Fourteen mares had ovarian neoplasia in either one or both ovaries, 10 mares had normal ovaries, and the ovaries of the remaining four mares were not examined to identify if cancer was present. Following ovariectomy, rideability improved in 80% (8/10) of mares with normal ovaries and in 57% (8/14) of mares with ovarian neoplasm. A behavioural improvement was observed in 40% (4/10) of mares with normal ovaries, and in 43% (6/14) of mares with ovarian neoplasm. Mares with unwanted behaviour not obviously related to the oestrus cycle and to painful conditions may benefit from ovariectomy to alter their behaviour and rideability.

Abstract

Unwanted behaviour in mares is a commonly presenting problem to the veterinarian. This behaviour may range from the mare being uncooperative or aggressive when handled on the ground, kicking, bucking or rearing when ridden or being aggressive towards other horses. This purpose of the study was to evaluate whether bilateral ovariectomy in mares with unwanted behaviour improved the mare’s behaviour and/or rideability from the owner’s perspective. The mares were grouped and compared statistically based on their histological classification as having either “normal” or neoplastic ovaries. This study is a retrospective case series report of twenty-eight ovariectomized mares. A semi-quantitative value (1–10) pre- and post-ovariectomy for A) behaviour on ground/in stable and B) rideability was given, based on the owner’s observations. The horses were grouped based on their histopathologic diagnosis as “Normal ovaries” or “Neoplasia”. Following ovariectomy, rideability improved, with a score of ≥5 in 80% (8/10) of mares with normal ovaries and in 57% (8/14) of mares with ovarian neoplasm. A behavioural improvement of ≥5 was observed in 40% (4/10) of mares with normal ovaries, and in 43% (6/14) of mares with ovarian neoplasm. A significant difference was observed between the semi-quantitative value pre- and post-ovariectomy in both groups. No difference was observed in change in behaviour and rideability score between the group with normal ovaries and neoplastic ovaries. Mares with unwanted behaviour not obviously related to the oestrus cycle and to painful conditions may benefit from ovariectomy to alter their behaviour and rideability.

Left paralumbar fossa approach combined with mesocolon fenestration for bilateral equine ovariectomy

OBJECTIVE

To describe a standing left paralumbar fossa approach combined with mesocolon fenestration for bilateral equine ovariectomy.

STUDY DESIGN

Prospective experimental clinical study.

ANIMALS

Four healthy client-owned mares and 1 client-owned Molly mule.

METHODS

Mares were restrained in standing stocks and sedated with an α2 -agonist continuous infusion to effect. The abdominal cavity was approached via a left paralumbar fossa approach, and the contralateral right ovary was accessed through an incision in the mesocolon. The location of the window was adjusted to allow triangulation, adequate visualization, and manipulation of the contralateral right ovary. Each ovarian pedicle was ligated with extracorporeal ligatures prior to sharp transection. The ovaries were dropped and left within the abdomen as part of another study. The incision in the mesocolon was closed with laparoscopic staples. Mares were monitored hourly while hospitalized, and a questionnaire was completed by the owners 90 days after surgery.

RESULTS

Both ovarian pedicles were successfully ligated and transected in all mares through the left paralumbar fossa approach and mesocolon fenestration. The only complications consisted of mild incisional emphysema in 2 of 5 equids, with all resolving spontaneously. All equids returned to intended use at 90 days.

CONCLUSION

The left paralumbar fossa approach combined with mesocolon fenestration provided adequate access to both ovaries with minimal morbidity in this small population.

CLINICAL SIGNIFICANCE

A unilateral left paralumbar fossa approach and fenestration of the mesocolon should be considered as an alternative to traditional approaches for bilateral laparoscopic ovariectomies in equids.

Double ovarian tumour in the mare: Case report

Ovarian tumours in mares represent 2.5% to 6% of the most frequent neoplasms found in the equine species, with a higher chance of benignity. This study aims to describe a case of two different tumours found in the same ovary of a mare that presented clinical signs of suppressed oestrous cycle during 5 years. After unilateral ovariectomy, the ovary was sent to the histopathology examination which determined a mixed tumour of granulosa cell and leiomyosarcoma. After treatment, the mare returned to oestrus and got pregnant in the next season.