Page 509 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

484 CHAPTER 2

VetBooks.ir haematomas may be present within the tumour, develop GCTs during pregnancy often continue
their pregnancy as normal, but they will have abnor-
leading to a distinctive appearance. The contralat-
eral ovary is usually small and fibrous, often showing
no cyclic activity. mal cyclic activity post partum.
The hormone levels often dictate the behavioural OTHER OVARIAN TUMOURS
signs that are displayed and they should always be
performed to diagnose (or confirm suspicions) prior Definition/overview
to surgery. The vast majority of mares will have Other tumours of the ovary include teratoma, ade-
raised serum inhibin levels (>700 ng/l [700 pg/ml]) or noma, cystadenoma, adenocarcinoma and dysgermi-
raised serum anti-müllerian hormone (>28.6 pmol/l noma. They are non-secretory, unilateral and usually
[4 ng/ml]). Testosterone levels are elevated in 50–60% not malignant except in the case of dysgerminoma
of cases (>0.17–0.35 nmol/l [50–100 pg/ml]) and pro- and adenocarcinoma. Teratoma is the second most
gesterone levels are invariably low (<3.18 nmol/l common ovarian tumour after GCT, but the others
[1 ng/ml]). Occasionally, oestrogen levels are raised. are rare.
Laparoscopy/laparotomy followed by histopa-
thology of the ovary after its removal will confirm Aetiology/pathophysiology
the diagnosis. Adenomas are epithelial and usually unilateral, aris-
ing most commonly at the ovulatory fossa or ovi-
Management ductal fimbriae. They are non-secretory, usually
Treatment is by surgical removal of the affected benign, can grow extremely large, are unilobular or
ovary via a flank or ventral midline laparotomy multilobular, and the contralateral ovary is usually
(Fig. 2.93), colpotomy or laparoscopy. Laparoscopy normal. When they become cystic they are referred
is the method of choice except when the ovary is very to as cystadenomas (Fig. 2.94). Rarely, non-cystic
large, when laparotomy may be necessary.

Prognosis 2.94
The prognosis for return to fertility is good, cyclic
activity usually resuming within 9 months of sur-
gery or the next breeding season if surgery is per-
formed late in the year. Metastasis is rare. Mares that

2.93

Fig. 2.93 Ovarian tumour being removed at
laparotomy using a stapling device. Note the enlarged Fig. 2.94 Transrectal ultrasonographic view of a left
ovary. ovary with a cystadenoma. (Photo courtesy Tracey
Chenier)