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Therio - Infertility in Mares 1

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drraythe's version from 2017-09-10 04:03

Abnormal 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
64, XY
What is the most common chromosomal abnormality in horses?63, XO gonadal dysgenesis (Equivalent to Turner’s Syndrome in people)
CSs of gonadal dysgenesis. How to dx?(Remember, chromosomal abnormality, 63XO instead of 64XX) extremely small ovaries, Infantile reproductive organs. Dx w/ 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 w/ behavioural anestrus present upon exam?Has normal cyclic ovarian activity: Regular cycles, Ovulation, Typical changes in uterus, cervix & vagina
Why might the mare w/ 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 w/ foal?
Anestrus → Seasonality & the Transition Period → when is the anestrus period & what will she be like upon exam?Nov-Jan, Mares ovaries will be small & inactive & non-cyclic
Anestrus → Seasonality & the Transition Period → when is the transition period? What will she be like upon exam?During spring/autumn. Mare’s ovaries will be large & active, w/ 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 1st ovulation occur post-partum?1st 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 1st « 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 & 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 & becomes filled w/ blood. May get very large (>10cm diameter), & are repeatable
What might be the cz of an anovulatory follicle?Possibly endocrine in nature – lack of GnRH/LH support
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Tumors

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 czs male-like BH?GCT
What is it about GCT that makes its CSs so strange? Complications of this?They are Secretory tumors & can produce estrogen, testosterone, & inhibin ***inhibin czs atrophy of contralateral ovary
Why might a mare have 1 really huge looking ovary & 1 super small one?Could be a GCT- huge on is where tumor is, & it's producing inhibin which czs 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?1 small atrophic ovary & 1 enormous ovary
How can you Dx a GCT w/ 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-müllerian hormone (AMH) almost diagnostic
*Which hormone assay is nearly diagnostic for GCT?High anti-müllerian hormone (AMH)
Tx of GCT?Sx removal
What is prog like for GCT (& why?)Prognosis is very good bc...
(1) Return to cyclicity in 3 mos to 2 yrs
(2) Return to normal fertility w/ 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 hormonally active, No effect on ovarian Fxn, & Contralateral ovary is active. No metastases! Very rare & 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 & active (vs. GCT where it is small & 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 hormonally inactive & slow growing. Tx w/ sx. Possibility for metastases :(
What does dysgerminoma appear on U/S?Ultrasound atypical image massive, echogenic structure
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Other stuff (Abnormal 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 persistent CL) could be czd by what things?Due to chronic uterine Infxn & fibrosis?, Pyometra
If EED occurs before endometrial cups are present, then estrus will be delayed...by how long?30d
If EED occurs & endometrial cups present, estrus will be delayed for up to... how long?150d
How can you Dx anestrus due to persistent CL?Teasing Hx, CL visible on ultrasound, Uterine & cervical tone, No edema
TX for anestrus due to persistent CL?Prostaglandin!
Etiology of pyometra often due to..?Inability of the cervix to open/relax
What are the major problems czd 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 affected 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 w/ large volumes) w/ mild disinfectant (Βetadine solution)
What chemical can you put in a cream to apply to cervix to cz it to dilate?PGE (prostaglandin E)
Prog of pyometra?High % reoccurrence! Permanently infertile? Take biopsy! Hysterectomy?
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