Ovarian Abnormalities in Mares Flashcards
Non-neoplastic - developmental
- parovarian cysts –> easy to confuse with antral follicles
- fimbral cysts –> fimbriae of the oviduct (paramesonephric)
- cystic epoophoron –> cranial ovary
- cystic paroophoron –> caudal ovary
- ectopic adrenal tissue –> adrenal cortex
Developmental
Notice which are outside the ovary
- cranial and caudal: outside
- fimbral: outside
- germinal inclusions: inside
- palpation and US
Non-neoplastic - acquired
- anovulatory follicles
- germinal inclusion cysts
- ovarian hematoma
Anovulatory follicle
Preovulatory follicle that fails to ovulate
- appear normal until prior to ovulation (usually too late)
- 5% in early season, 20% in late
- commonly associated with older mares, or mares with a prior history
- contents range from uniformly hypoechoic to cobweb appearance
Anovulatory follicle - process
Majority luteinize and produce progesterone
- eventually become PG-responsive
- can last for weeks to months
- continue to monitor the other ovary for activity as these do not affect the contralateral ovary
Germinal inclusion cysts
Peritoneum becomes embedded in ovulation fossa
- should be smaller than typical follicle
Ovarian hematoma
Excessive hemorrhage into folliclular lumen
- 50 mm up
- occurs immediately after ovulation!
- dont confuse with ovarian tumor or anovulatory follicle
- rarely pathogenic
- functional life span of luteal tissue is normal
Ovarian hematoma - life span
Can last for several cycles
- contralateral ovary continues to cycle –> could breed on the other ovary
- major concern is effacement of ovary
Neoplastic
- sex cord (gonadostromal) tumors: granulosa-theca cell, arrhenoblastoma
- epithelial tumors: cystadenoma, adenocarcinoma
- mesenchymal tumors: hemangioma, leiomyoma, fibroma
- germ cell tumors: teratoma, dysgerminoma
**Gonadostromal (sex cord) tumors - granulosa theca cell tumor
Most common reproductive tract tumor: 2.5% of all equine neoplasms
- barren, pregnant, maiden mares affected
- hormonally active
- elevated inhibin in 90% of cases: inhibin >0.7 ng/ml is elevated
- elevated testosterone in 50-60% of cases: from theca cell component, T > 50-100 pg/ml is elevated
- inactive contralateral ovary: downregulation of FSH by inhibin and GnRH by testosterone
- usually not cycling at time of discovery!
Granulosa-theca cell tumor - behavior
- prolonged anestrus
- continuous or intermittent estrus (nymphomania)
- stallion like behavior
- varies depending on which hormones are secreted and amounts
Granulosa-theca cell tumor - diagnosis
- progesterone is usually low
- testosterone is high in 48% of cases
- inhibin is high in 80% of cases
- anti-mullerian hormone: elevated in 98% of confirmed cases (>8.0 ng/ml is consistent with GCT)
- UC-Davis endocrinology lab
- definitive: histopathology of tumor
Granulosa-theca cell tumor - surgical removal
- colpotomy
- flank laparotomy
- ventral midline laparotomy
Granulosa-theca cell tumor - prognosis
Contralateral ovary resumes cyclicity generally within a year
Germ cell tumors - teratoma
Accidental finding in non-breeding animals
- benign germ cell tumor
- totipotent cells
- must have 2 or more germinal layers and multiple tissues present: mesoderm, endoderm, ectoderm
