Parturition

Question 1

what is parturition?

Answer 1

• delivery of fetus
• passage of the fetal membranes (placenta)

Question 2

what is the function of the placenta?

Answer 2

it is a fetomaternal organ with a fetal component developing from a blastocyst, and a maternal component developing from maternal endometrium

Question 3

a dog’s temperature should be between 101 and 102.5 degrees. when the temp drops below _______, when will the puppies be delivered?

Answer 3

below 100 = she should deliver the pups in less than 24 hours

Question 4

what hormonal change is often useful in predicting parturition?

Answer 4

LH surge in dogs: 1 event that lasts less than 24 hours and is useful in predicting day of whelping

Question 5

what behavioral changes can be noted that will indicate parturition occurring soon?

Answer 5

segregation, nesting, anorexia, restlessness

Question 6

what determines the “readiness for birth”?

Answer 6

the maturation of the fetus

Question 7

what physical feature might you notice on mares that indicates parturition will be occurring soon?

Answer 7

ventral edema
- risk factor for ligaments or muscles tearing but will go away after birth
- prevent it by hand-walking
- lymphatics are blocked off, so plaque of edema will build up

Question 8

what physical features might you notice when an animal is about to give birth?

Answer 8

• relaxation around pelvis and perineum
• vulva becomes edematous and relaxed
• mammary enlargement, dilation of teat ends
• ventral edema in cows and mare
• leaking milk
• waxing of teat ends in mare: colostrum that has leaked/dried

Question 9

what is the signal for parturition in many species?

Answer 9

fetal ACTH and cortisol
the rise in cortisol is what triggers the increase in estradiol and decrease in progesterone

Question 10

what triggers parturition?

Answer 10

when the fetus is physiologically ready to survive outside the uterus. the fetus sends a signal to the dam to initiate parturition

Question 11

does cortisol increase or decrease estradiol or progesterone?

Answer 11

increases estradiol
decreases progesterone

Question 12

what drives parturition?

Answer 12

prostaglandins and oxytocin, which stimulate myometrial contractions

Question 13

how does fetal stress/maturation affect oxytocin?

Answer 13

fetal stress increases ACTH, which increase cortisol, which eventually causes an increase in oxytocin

Question 14

what is the final hormone that is the trigger/stimulus for birth in sheep and cattle?

Answer 14

cortisol

Question 15

removal of the pituitary or adrenal gland from the fetus within pregnant ewes results in

Answer 15

prolonged pregnancy = no ACTH, no cortisol
if you remove ACTH and thus cortisol, then fetus cannot make the signal for the birth process, and you see a prolonged gestation

Question 16

administration of ACTH or cortisol to the ovine fetus would result in

Answer 16

premature labor: ACTH would stimulate fetal cortisol secretion
- ACTH is big hormone, cortisol is steroid. cortisol crosses placenta, ACTH does not. if you give ACTH to pregnant ewe, it will not stimulate the ewe, but if you give cortisol to a pregnant ewe, it will cross and will stimulate the birth process

Question 17

if you want to stimulate early labor, should you administer ACTH or cortisol to the dam?

Answer 17

cortisol, because it is a steroid and will cross the placental barrier to stimulate the birth process. ACTH will not stimulate the fetus because it won’t cross

Question 18

can you give dexamethasone to a dam to stimulate labor?

Answer 18

yes, because it mimics cortisol and will stimulate birth process (corticosteroid)
- CAUTION THO: do not use in camelids!! causes pregnancy loss!!

Question 19

what should you NOT administer in pregnant camelids?

Answer 19

corticosteroids!!! don’t even use an eye ointment containing steroids! causes pregnancy loss.

be cautious in ruminants!! use caution

Question 20

you should be cautious about steroid use in what pregnantspecies

Answer 20

CAMELIDS and ruminants

Question 21

what events does fetal cortisol trigger leading to parturition?

Answer 21

• placental estrogen production increases, progesterone decreases
• results in increased E:P ratio
• PGF2a secreted from placenta and endometrium
• oxytocin receptor numbers increase on myometrial cells

Question 21

PGF2a induces

Answer 21

uterine contractions
as soon as prostaglandins cause contractions and push the fetus up against the cervix, the fetus stretches it and there is a reflex release of oxytocin from the posterior pituitary

Question 23

what does parturition look like in CL dependent species?

Answer 23

• goats, sows
• fetal cortisol initiates parturition, and placental estrogen increases
• PGF2a release causes regression of the maternal CL (luteolysis)
• labor begins as maternal progesterone concentrations decline

Question 24

what does parturition look like in litter bearing species?

Answer 24

- sow, bitch, queen - parturition is initiated by signals from entire litter - one early maturing fetus cannot trigger labor - rapidly maturing feti may be favored. need multiple mature feti to be able to trigger labor

Question 25

T/F: one early maturing fetus in a pig has the possibility to trigger labor.

Answer 25

false

Question 26

what are the 3 stages of labor?

Answer 26

1. initiation of myometrial contractions: removal of progesterone block 2. delivery/expulsion of fetus 3. passage of the fetal membranes: placenta

Question 27

stage 1 labor onset and end

Answer 27

onset: initial uterine contractions and relaxation of cervix end: rupture of chorioallantois (LA) or full dilation of cervix (SA): don't really break fluid; get full dilation of cervix

Question 28

what are clinical signs of stage 1 of labor?

Answer 28

 Anorexia  Restlessness, nervousness  Frequent lying downing and standing  Mild discomfort or colic  Patchy sweating (mare)  Increased respiratory rate (bitch)  Actively running or squirting milk  Thick string of mucus from vulva (cows)

Question 30

how long does stage 1 of labor last in a cow?

Answer 30

2-6 hours

Question 32

what fetal movement occurs during stage 1 of labor?

Answer 32

head and forelimbs extend, body rotates into dorsal position

Question 33

what marks the end of stage 1 of labor?

Answer 33

rupture of chorioallantoic membrane "water breaks"

Question 34

what is stage 2 of labor onset and end

Answer 34

onset: rupture of chorioallantois end: delivery of fetus

Question 35

what are clinical signs of stage 2 of labor?

Answer 35

- active straining - appearance of white/grey translucent membrane (amnion) at vulva - birth of fetus

Question 36

how long does stage 2 of labor last in different species?

Answer 36

cow: 30-60 mins mare: 12-30 mins bitch: 6 hours longer in primiparous dams danger if there is a delay in the birth process because placenta can separate and then loss of placental contact with endometrium means fetus has lost O2 contact

Question 37

what is onset and end of stage 3 labor?

Answer 37

onset: delivery of fetus end: passage of fetal membranes

Question 38

how long does stage 3 of labor last in a horse? why is this critical?

Answer 38

15 min-3 hours. in a horse, we consider placenta to be abnormally retained at 3 hours!! a cow can have a placenta even for a couple days and won't get systemically ill, but in a horse will get endotoxemic, laminitis, etc

Question 39

how long does does stage 3 labor last in cow?

Answer 39

0.5-8 hours

Question 40

how long does stage 3 labor last in bitch?

Answer 40

fetal membranes expelled irregularly between fetuses. dam alternates between stage 2 and 3 as each fetus is delivered

Question 41

placentophagia

Answer 41

- dams of many domestic animal species eat their placentas - may cause choke or colic in large animals

Question 42

how can you induce labor in major species?

Answer 42

ruminants: corticosteroids. but be careful because if given too early get immature fetus with no survival abilities CL dependent species: prostaglandins horses: oxytocin