Therio- Infertility in Mares 1

wilsbach's version from 2015-11-10 22:28

not having normal cycles

Question Answer
if the mare has never cycled normally, what 2 things might you consider to be the problem?(1) chromosomal (2) congenital
what is the Karyotype (chromosome thing) of normal horses?64, XX and 64, XY
what is the most common chromosomal abnormality in horses?63, XO gonadal dysgenesis (Equivalent to Turner’s Syndrome in people)
clinical signs of gonadal dysgenesis? how to dx?(remember, chromosomal abnormality, 63XO instead of 64XX) Extremely small ovaries, Infantile reproductive organs. Dx with Karyotyping
If the mare is not having normal cycles, consider what 6 things?(1) Seasonality (2) Anestrous (3) Prolonged diestrus (4) Anovulatory follicles (5) Ovarian tumors (6) Pyometra
what types/reasons for anestrus?(1) Behaviour anestrus (“Silent heat”) (2) Seasonal anestrus (3) Anovulatory follicles
how does a mare with behavioural anestrus present upon exam?has normal cyclic ovarian activity: Regular cycles, Ovulation, Typical changes in uterus, cervix and vagina
why might the mare with b/h anestrus not "show" to the stallion?(1) Grey stallion (some mares just dont like grey stallions apparently) (2) Shy, maiden mare? (3) Mare with foal?
anestrus--> Seasonality & the Transition Period--> when is the anestrus period and what will she be like upon exam?Nov-Jan, Mares ovaries will be small & inactive and non-cyclic
anestrus--> Seasonality & the Transition Period--> when is the transition period? and what will she be like upon exam?during spring/autumn. Mare’s ovaries will be large and active, with several follicles, Irregular estrous cycles
how soon post-partum can a mare go into estrus? what is this called?On average mares are in estrus as early as 5 to 14 days postpartum – « Foal Heat »
when does the first ovulation occur post-partum?First ovulation occurs on average around 9 days postpartum
how might an old mare that foals early in the year's cycle be different?may revert to anestrus (usually after the first « foal » heat.) Is not nutritional but seasonal inducted
how can you prevent a seasonal anestrus?Can be prevented by placing pregnant mares under artificial photoperiod
when do Anovulatory follicles usually happen? when is this normal and when is it not normal?Normally occur during Spring or Autumn transition period. A problem if occur during the breeding season
what is an anovulatory follicle?Follicle doesn’t ovulate--> Dominant follicle fails to ovulate and becomes filled with blood. May get very large (>10cm diamter), and are repeatable
what might be the cause of an anovulatory follicle?Possibly endocrine in nature – lack of GnRH/LH support


Question Answer
*what is the most common type of ovarian tumor?Granulosa cell tumour (GCT)
4 types of ovarian tumors?(1) Granulosa cell tumor (most common) (2) Teratoma (2nd most common) (3) Dysgerminoma (4) Cystadenoma
teratoma- benign or malig? how will it appear histologically?benign, Could be any type of tissue (germ cell tumor)
dysgerminoma- benign or malig? from what cells?Malignant & metastasize, tumor of Primordial germ cells
is granulosa cell tumor (GCT) malig or benign? how does it present in terms of location etcUnilateral, slow growing & benign. Destroy normal ovarian architecture
which ovarian tumor causes male-like bh?GCT
what is it about GCT that makes it's clinical signs so strange? complications of this?They are Secretory tumors and can produce estrogen, testosterone, and inhibin ***inhibin causes atrophy of contralateral ovary
why might a mare have one really huge looking ovary and one super small one?could be a GCT- huge on is where tumor is, and it's producing inhibin which causes atrophy of contralateral ovary
what are the CS of a GCT in a mare?Aggression & stallion-like behaviour, Masculine neck muscle development, Irregular estrous cycles, Anestrus 25%
how can you dx a GCT via rectal palpation?One small atrophic ovary & one enormous ovary
how can you dx a GCT with U/S?Honeycomb appearance on U/S
4 hormone assays you can do to try to dx a GCT?(1) Increased inhibin (2) Increased testosterone (3) Low progesterone (4) High anti-mullerian hormone (AMH) almost diagnostic
*which hormone assay is nearly diagnostic for GCT?High anti-mullerian hormone (AMH)
tx of GCT?sx removal
what is prog like for GCT (and why?)Prognosis is very good because... (1) Return to cyclicity in 3 months to 2 years (2) Return to normal fertility with regular estrous cycles (3) No (minimal) risk for metastasis
teratoma: cells of origin? Is it hormonally active? does it affect the fxn of the ovary/ contralateral ovary? does it metastasize? tx?Origin: germinal cells, Not hormonaly active, No effect on ovarian function, and Contralateral ovary is active. No metastases! Very rare and chance finding, removal not necessary
Cystadenoma: cells of origin? how is the ovary affected? contralateral ovary? does it metastasize? tx?Neoplasia of the superficial epithelium of the ovary. Enlarged, absence of ovulation fossa, Contralateral ovary is normal and active (vs. GCT where it is small and inactive). Very slowly enlarging, Surgery but not urgent, no metastasis.
how does a cystadenoma appear on U/S?spectacular large number of small cysts (honeycomb) DDx: GCT
dysgerminoma: cells of origin? how does the affected ovary appear? contralateral ovary? does it have hormonal involvement? tx? does it metastasize?Germ cell tumor. Ovary is Enlarged, no ovulation fossa. Contralateral ovary is active. The tumor is Hormonaly inactive and slow growing. Tx with sx. Possibility for metastases :(
what does dysgerminoma appear on U/S?Ultrasound atypical image massive, echogenic structure

other stuff (not having normal cycles)

Question Answer
prolonged diestrus--> PERSISTANT CL. What are 3 cases where the CL failed to regress at an expected time?(1) Failure of sufficient PGF secretion by uterus (2) Presence of an immature CL due to a diestral ovulation (3) EED after maternal recognition of pregnancy (+/- D16) (Pseudopregnancy)
Failure of sufficient PGF secretion by uterus (leading to persistant CL) could be caused by what things?Due to chronic uterine infection & fibrosis?, Pyometra
If EED occurs before endometrial cups are present, then estrus will be how long?30d
if EED occurs and endometrial cups present, estrus will be delayed for up to.... how long?150d
how can you dx anestrus due to persistant CL?Teasing history, CL visible on ultrasound, Uterine and cervical tone, No edema
tx for anestrus due to persistant CL?Prostaglandin!
etiology of pyometra often due to..?inability of the cervix to open/relax
what are the major problems caused by pyometra?Endometrium is severely damaged: no PGF release – future fertility severely compromised – take a biopsy!!
dx of pyometra?anestrus – enlarged uterus - ultrasonography
how does pyo look like on U/S?
how is the mare systemically affeced by pyometra?Mare is not systemically ill: no fever, no endotoxemia
how do you tx pyometra? (2 major steps)(1) Manual dilation - use of PGE cream applied locally on the cervix (2) Uterine lavage (repeatedly with large volumes) with mild disinfectant (Betadine solution)
what chemical can you put in a cream to apply to cervix to cause it to dilate?PGE (prostaglandin E)
prog of pyometra?High % reoccurance! Permanently infertile? Take biopsy! Hysterectomy?

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