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Reproduction > equine pregnancy > Flashcards

equine pregnancy Flashcards

1
Q

early events of pregnancy

A

commences with mating/insemination and fertilization

billions of sperm ejaculated into mare uterus- few thousand to oviduct via tube-uterine junction

sperm= morphologically normal, stored in oviduct until oocyte transported from fimbrial end

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2
Q

day 0

A

sperm are deposited in repro tract concurrent with pre-ovulatory follicle
after adequate maturation, follicle ruptures and releases the oocyte

day of ovulation= 0

CL, present in both diestrus and early pregnancy in the mare, produces progesterone

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3
Q

endocrinology of pregnancy

A

early pregnancy supported by ovarian progesterone
secondary CL supply support in addition to primary (1st third of pregnancy)

later 2/3 of pregnancy supported by progestin produced by fetoplacental unit, during this part of gestation, progesterone= at baseline conc.

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4
Q

hormones and days

A

day 0= increasing progesterone
estrogen low

day 40= increasing ovarian progesterone until around day 100, ovarian estrogen follows same pattern but at lower concentration

day 160= fetoplacental estrogen increasing as ovarian progesterone falling along with estrogen
fetoplacental 5a-pregnanes start increasing

day 335- parturition= decline of progesterone and great rise in 5a

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5
Q

oviductal events in mare

A

infundibulum- covers ovulation fossa
isthmus
ampulla- sperm passage
fertilization- ampullary isthmic junction

preovulatory follicle ovulated to fimbriae then ovum transported and fertilized in ampullary-isthmic junction

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6
Q

embryo transport to uterus

A

day 5.5 to 6

enters uterine lumen

embryonic transport through oviduct facilitated by prostaglandin E from embryo which also allows for relaxation of uterotubal junction

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7
Q

compact morula

A

early embryo cleaves multiple times to form while in oviduct

contained within the zona pellucida

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8
Q

blastocyst

A

early uterine embryo developed to blastocyst stage and shed its zona pellucida

glycoprotein coating (capsule) replaces zona pellucida which is unique to the horse

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9
Q

Capsule

A

role in shape maintenance (18-20 days of pregnancy)

spherical shape= imps. for movement of embryo through uterus and maternal recognition of pregnancy

thought to protect the embryo as it moves through the uterus because highly motile

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10
Q

expanded blastocyst

A

can see inner cell mass

commonly flushed from uterus at day 7-8

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11
Q

unfertilized oocyte

A

do not produce PGE, retained in oviduct

strong indication that embryo is present if seen post flush

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12
Q

early detection of pregnancy

A

day 13-15 post ovulation

mare can ovulate multiple follicles days apart

impt. for detection of twins which is typically due to double ovulation a few days apart

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13
Q

twins

A

not well tolerated due to placentation

reduction of twins= best option because don’t get placental help needed

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14
Q

mobility and fixation of conceptus

A

equine embryo highly mobile for first 16-17 days of gestation- traverse both uterine horns and uterine body

impt. for maternal recognition of pregnancy (twins also do this)

increasing size of vesicle as well as increased uterine tone, embryo becomes fixed at base of uterine horn around day 17

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15
Q

early embryo nutrition

A

relies on yolk sac and uterine glands

yolk sac= transient, provides nutrition to embryo for ~ first 40 days

histiotrophe- produced by uterine glands, source of nutrition for the embryo until placentation develops

glands= instrumental for nutritional support

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16
Q

endometrial cups

A

day 37

result from migration of trophoblastic cells into endometrium ~36-37 days gestation

endometrial cups secrete equine chorionic gonadotropin which is like LH, impt. for early pregnancy maintenance

17
Q

Equine Chorionic gonadotropin

A

responsible for formation of secondary CL which are essential to pregnancy maintenance

secondary CL secrete progesterone until about 100-120 days of gestation at which time the placenta fully formed

P4 high near day 0= primary CL, primary CL along with eCG increases and then along with accessory CL peak around day 100

18
Q

ovarian progesterone

A

due to secondary CL

later 2/3 gestation fetoplacental unit produces progestins

19
Q

placentation

A

diffuse, epitheliochorial, non-deciduate (non invasive) and microplacentomes

microcotyledons interdigitate with endometrium to provide fetal support (if compromised then premature delivery)

20
Q

factors impt. for parturition

A

length of gestation, fetal maturation, colostrum production, cervical dilation

21
Q

length of gestation

A

highly variable (320-360 days)

each mare has own gestational length, repeatable year after year

affected by day length and season

22
Q

fetal maturation

A

occurs in last week of gestation

cortisol rise in last 48 hrs, premature delivery devastating because cortisol not yet secreted

adrenal reaches critical weight and begins production of fetal cortisol indicating fetal maturity and readiness for birth

fetal lamb and piglet undergo final maturational changes initiated by cortisol in weeks prior to delivery

23
Q

cortisol

A

does not rise in equine pregnancy until last 24-48 hrs prior to delivery

24
Q

premature delivery

A

results in neonate that is not well prepared for extrauterine life

25
Q

colostrum production

A

multiparous mare develops mammary glands 2-4 wks prior to foaling

maiden mares can have small udder or late development

colostrum prod. critical for conferring immunity to naive equine neonate

bulk of colostrum= produced in last 48 hrs of gestation

production of milk= essential for survival

26
Q

mammary secretion electrolytes

A

changes correlated with fetal maturity

Ca2+> 40 mg/dl

increase K+ and decrease Na+

indicator of when might foal, if considered for induced parturition values= impt. for optimizing the ability of neonate to survive outside of uterus

27
Q

cervical dilation

A

occurs prior to parturition, faster delivery
improved neonatal adaptability

critical for delivery, if closed cervix delivery slowed and foal experiences hypoxia

28
Q

hormones and cortisol

A

final days of pregnancy- along with rise in cortisol, rise in fetoplacental progestogen conc. and fall in estrogen which initiate parturition

opposite of sheep where progesterone decreases and estrogen increases

29
Q

stages of parturition

A

Stage I= 1-4 hrs
II= 30-60 min
III= greater than 3 hrs

30
Q

stage I

A

wander around stall

fetus orients self in birth canal- rearrange

31
Q

stage II

A

30-60 minutes

ends with delivery of the fetus

32
Q

stage III

A

placental expulsion
>3 hours considered retained
can be an emergency

Reproduction (22 decks)

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