Therio - Mare Gestation

drraythe's version from 2017-10-10 15:38

Starting w/ fert

Question Answer
Where does fert occur?Oviduct
How long is the embryo in the oviduct before it migrates to the uterus?+/- 6d
How long does the embryo remain round & mobile in the uterus after passing from the oviduct?Until D14
What does early preg factor & PGE (prostaglandin E) do, & where does it come from?Embryo secretes these, helps w/ keeping up motility of embryo (helps w/ material recognition of preg)
What determines maternal recognition of pregnancy?Eembryo is mobile (mobility affected by embryo secreting early preg factor & prostaglandin E aka PGE) & in contact w/ all parts of endometrium, & uterus has high tone (progesterone) which helps foal get to all parts of uterus
After how many days does the embryo finally fixate in the uterus, & where?D16, at base of uterine horn
(Movement previous to this is important for maternal rec of pregnancy)
4 ways for us to Dx pregnancy(1) Failure to return to estrus
(2) *Palpation per rectum
(3) *Ultra sound
(4) Hormonal assays
You can Dx preg via transrectal U/S by what day?D12!!!
How can you differentiate an embryo from a cyst?Until about D14 the embryo is perfectly round (cysts arent) & then also they have specular reflections (hyperechoic white stripes) which are dorsal & ventral to the round embryo. (Cysts dont have these)
How long does an embryo stay perfectly round? When does it begin to lose its shape?Round until about D16. After that, it fixates to uterus near base of horn, & starts to lose its shape.
Recognize what stages these are!!Yeah I know the days are on the pic w/e - Its Fixation, where the embryo fixates to the uterine horn and loses its perfectly round shape
From what day can you start to ID the embryo proper w/ U/S?D21
What is this & what stage?This is where you are just able to recognize the embryo proper, so it's D21
When can you recognize heartbeat w/ U/S?D25
What are we looking at here? This is seeing the fetal heartbeat (D25)
What is going on here & what stage is it based on this pic? The embryo has moved to the center of the embryonic vesicle, which means it is about D30
When does the embryo move to the center of the embryonic vesicle?D30
When does the embryo move to the top of the vesicle? At this point, what can you see?D40, only allantois is visible
What is going on here? Around D40, embryo moves to top of embryonic vesicle. Then by D50, embryo moves to bottom of vesicle & umbilicus is visible
When does the embryo move to the bottom of the vesicle, & what can you see at this point?D50, you can see the umbilical cord days in order of stuff you can seeD12, you can see the round embryo
After D16 it has fixated & is no longer perfectly around
D21, you can see the embryo proper, not just the vesicle
D25, fetal heartbeat
D30, yingyang (embryo at middle of vesicle)
D40, at top of vesicle
D50, bottom of vesicle w/ umbilical cord visible
***What is the most common NON-INFECTIOUS cz of abortion in horses??TWINS
Why must you always try to detect if there are twins?Most common non-infectious cz of abortion in horses!
By when should you "squash" 1 of the twins in a mare?Need to squash 1 while still mobile ie before D16, or AT LEAST BEFORE D35 when the endometrial cups appear & entire breeding season will be lost
If you have "squashed" 1 of the twins to prevent problems, what MUST you do?ALWAYS FOLLOW UP SCANS TO MAKE SURE ONLY 1 SINGLETON IS LEFT
DDx for twin detection is? How can you differentiate from twins?DDx is endometrial cysts - however, cysts are not mobile so you can map their position
Wuts dis? These are cysts!! They will not be mobile, you can map them & will be there before the mare is preg
Twins are usually bc of what 2 situations of ovulations?(1) Synchronous ovulations (<24h btwn ovulations)
(2) Non-synchronous ovulations (>24h btwn ovulations)
What type of twins (monozygous or dizygous) are horses usually?Dizygous (As in, 2 oocytes)
In the natural world, what usually happens w/ mares & twins?Usually in 60% of cases, it spontaneously resolves (one of them dies). Usually this depends on implantation site & disparity in size btwn embryos. Resolution usually happens much more commonly if implanted unilaterally (same horn) bc of competition.
If one does not die, then mare will prob end up aborting both
When is the best time to try to sex embryos via US? What are you looking for? Which type of horse do you especially care about sexing w/?D55-65 is optimum. Looking for position of genital tubercle. Usually care a lot if it is a polo pony (want fillies).
When can you sex the fetus w/ trans-ABDOMINAL U/S (as opposed to transrectal)D80-90
Rectal PALPATION preg Dx - when can you feel inc cervical & uterine tone?D15-18
Rectal PALPATION preg Dx - when can you detect ventral bulge at base of uterine horn?D20-25
Rectal PALPATION preg Dx - when can you do ballottement of fetus?D90-120
3 DDx for pregnancy via rectal palpation?Urinary bladder
Distended large bowel
Name the things in order, w/ the days in which they occur, of what you can Dx preg by via rectal palpationInc cervical & uterine tone D15-18 → ventral bulge at base of uterine horn D20-25 → ballottement of fetus D90-120

Maintaining, more basics, etc...

Question Answer
Why might you want to do a hormone assay instead of
or supplemental to rectal palpation?
Fractious (grumpy) mare
Inadequate equipment/facilities
Mare size (minis/ponies)
Compromised rectum
Operator inexperience
What are the hormone assays available to check for preg?(1) Progesterone
(2) eCG (IT SAYS E NOT H) (they can't produce hCG bc they are not HUMANS)
(3) Estrone sulphate
(4) Urinary estrogens
(5) Early conception factor
*What are the 3 main sources of progesterone during preg (& the times in which they are sustained)(1) D0-D180 is 1° CL
(2) D40-90 2° CLs (induced by endometrial cups)
(3) >D60-80 is fetal-placental progestagens (5α-pregnane) to maintain preg
From what days in the preg does the 1° CL act as the main source of progesterone?D0 to D180
From what days in the preg do the 2° CLs act as the main source of progesterone?D40-90
From what days in the preg does the fetal-placental progestagens act as the main source of progesterone?> D60 (detect on D90 to Dx Pregnancy)
What must you absolutely keep in mind about detecting progesterone for pregnancies? (DDxs?)NOT DIAGNOSTIC OF PREG - false pos can be czd by prolonged luteal phase (diestral ovulation) or perhaps there was Early Embryonic Death (EED)
What are the 2 serum chemicals you can use to diagnose pregnancy in the mare?eCG & estrone sulphate
eCG aka? Where does it come from & from what days can you detect it?Equine chorionic gonadotropin, previously PMSG (pregnant mare serum gonadotropin) is secreted from the endometrial cups & can be detected from D40-D120
When might you get a false pos for pregnancy from measuring serum eCG?False pos if fetal death occurs after endometrial cup formation
Estrone sulfate is what? Is used to do what? Is detected from what days & comes from what sources?Way to Dx pregnancy - comes from a luteal source D35-40 & after that (>D60) fetoplacental source HOWEVER, amts that are Dx of pregnancy is by D90 should be >6ng/ml. Can also be used to check fetal viability prior to 7mo gestation
*What are the 2 things you can determine from detecting levels of estrone sulfate?(1) Pregnancy if by D90 >6 ng/ml
(2) Check fetal viability if prior to 7mo of gestation
*3 things that maintain preg, & WHEN they are being effective at doing this(1) 1° CL
(2) D35 to D120 endometrial cups (induced 2° CLs)
(3) 5α-pregnane from fetal-placental unit
What are endometrial cups & why are they helpful?Trophoblastic cells of fetal origin which burrow into endometrium of mare, & then secrete eCG which czs resurgence of 1° CL & development of 2° CLs
Pic of stuff that's maintaining preg when
What type of placentation?Diffuse, epitheliochorial
Normal gestation length?335-342d
Under how many days of gestation would be considered abortion?<300d
From what range of days would a born foal be considered premature & non-viable w/o care?300-320d
How many days would be considered prolonged gestation?>360d
Why might a prolonged gestation be considered pathological?Might be pathology due to fescue tox (ingestion of ergot alkaloids in endophyte fungus ie Acremonium coenephialum)
(also causes agalactia - give Domperidone (dopamine antagonist) )

Preparation for foaling/foaling

Question Answer
How long before foaling should you introduce the mare to the foaling environment?4-6wk
What are the best & worst places for foaling?Best is outside on the grass
Stall/barn on straw is also suitable
Wood shavings are NOT SUITABLE
Why do you want to introduce the mare to the foaling environment 4-6wk before foaling?Reduces stress
Allows mare to build up immunity
Allows for Ab xfer to colostrum
In the last mo, mares should be monitored for..(6)(1) Vulvar laxity & edema (& elongation)
(2) Vulva discharge (cervical plug)
(3) Relaxation of pelvic ligaments
(4) Udder development
(5) "Waxing" of teats
(6) Changes in composition, consistency & color of milk
What does the vulva start to look like under the influence of Relaxin?
What do the sacrosciatic ligaments start to look like under the influence of relaxin?
Which hormone is responsible for the teat "filling in", & how do you know when they are close to parturition in regards to the teat? *What is important for you to do at this time?Teat fills in under the influence of Relaxin. When it is close to parturition, the wax cone "Stopper" falls off & milk start to drip. COLLECT COLOSTRUM!
How does milk consistency & color change when she is close to parturition?Goes from thick, sticky & yellow to more watery, lighter, & less stick as partus approaches
How does the milk's electrolyte & pH change as the mare nears parturition?Na+ dec, K+ inc (cross over w/ K+ in the last few days), Ca++ inc in the last 1-3d, & pH dec
How do ppl take advantage of the fact that the milk's electrolytes & pH change when nearing foaling? (How do you interpret it?)pH/electrolyte kits (look like urine dip stick tests) to help predict foaling. So, if only 1/5 squares change then there is a <1% chance mare will foal in next 12hr. if 4/5 squares have changed though, then there is an 80% chance mare will foal in next 24hr (neat)
3 stages of parturition? (& how long do they last?)(1) Preparatory stage (30min-4hr)
(2) Expulsion of fetus (5-20min)
(3) Expulsion of placenta (2-6hr)
What 3 main things are happening during the preparatory stage?Uterine contractility inc (contractions aren't visible yet tho!)
Dilation of cervix
Repositioning ("turning") of the foal
What will the mare look like during the preparatory stage?Restless, looking at flank, sweating, inc HR & RR. Frequent urination, lying down & standing up (this helps re-position the foal), pawing, elevation of tail
How does the foal reposition during the preparatory phase?Foal rotates from dorsopubic to dorso-illial to dorsosacral
What does stage 2 (expulsion of the fetus) start w/? What then happens?Starts w/ rupture of allantochorion (water breaks)
Then there are abdominal contractions & release of Oxytocin (Fergusons reflex)
Amnion is forced btwn vulvar lips
STRONG abdominal contractions → foal is born!
Where in the repro tract does the allantochorion break?Breaks at the level of the cervix - amnion remains intact.
When does the umbilicus rupture? Where does it rupture?Umbilicus will often stay totally intact even when foal is fully out of pelvis. However, it usually breaks when the foal/mare stands up, usually about 1-2 inches from abdominal wall.
Should you ligate the umbilicus? Should you disinfect it?DO NOT LIGATE unless bleeding excessively. Disinfect w/ chlorohex NOT ΒETADINE
What structures are w/in the umbilicus?The umbilical vessels (2 arteries, 1 vein) & the urachus
Expulsion of the fetal membranes usually occurs & is complete in how much time after foaling? When is it retained?Usu 30min-3hrs after foaling, but can be up to 6 hrs, >12h is RETAINED
Which breeds are very sensitive to retained fetal membranes?Friesians & Draft horses