Test 4: parturition Flashcards
The physiological processes involved in the birth of offspring which includes the delivery of the fetus and fetal membranes through the vaginal canal and involution of the uterus.
parturition
Processes Involved with Parturition
• Myometrial ___
- ____ of the birth canal
- Maternal abdominal straining
- Expulsion of the fetus
- Expulsion of the ___
- Onset of lactogenesis
- Development of maternal behavior
contractions
Relaxation and dilation
fetal membranes and fluids
how does ACTH affect pregnancy
Increase fetal ACTH
- Elevation of cortisol causes conversion of progesterone → estrogen by placenta
- Estrogens increase and cause the synthesis of PGF-2alpha by the uterus
• Cervix softens • Uterus contracts
___ will decrease and ___ will increase to cause cervix to soften and uterus to contract
progesterone
estrogen
___ cause uterine contractions
PGF2alpha
oxytocin
___ are luteal dependent
doe
sow
bitch
camelids
___ are not CL dependent
will get progestogen from the conceptus
Ewe –after 50 days • Mare –after 60 days • Queen-after 45 days
cortisol in cattle, goats and swine
these are luteal dependent (need CL to produce progesterone throughout the entire pregnancy)
Cortisol stimulates placental estrogen production
- Uterine release of PGF2α
- Rapid luteolysis→ CL dies
- Progesterone decreases
• Cervix relaxation • Uterine contractions
In cattle, goats, and sows, the circulating cortisol stimulates placental estrogen production causing uterine release of PGF-2α and rapid luteolysis of the CL, which results in a rapid decline in progesterone concentrations and subsequent uterine contractions. Cortisol production by the fetus during late gestation is essential for rapid lung maturation and the production of pulmonary surfactant, which is necessary for the survival of the fetus. Also during late gestation, there is an increase in estrogens and relaxin. Along with the rapid decline in progestogens and rise in prostaglandins, uterine contractions occur, the cervix softens and dilates, and parturition results. As the fetus enters the birth canal, The Ferguson Reflex occurs and oxytocin is released from the posterior pituitary. Oxytocin along with PGF-2α causes peristaltic uterine contractions, which result in delivery of the fetus and placenta. Estrogens are important in inducing receptors in the uterine tissue for oxytocin.
___ enzymes are needed to convert progesterone to estrogen(estradiol)
17 alpha hydroxylase
17-20 desmolase
aromatase
hormone profile of cow during parturition
cortisol increases and convert progesterone → estrogen
this causes release of PGF2alpha
progesterone decreases
cervix relaxes and uterine contraction
estrogen causes
secretion of the repro tract
increased contraction → oxytocin
how does PGF2 effect uterus
ferguson reflex
stretching of the cervix causes release of oxytocin which will cause uterus to contract → positive feedback
signs of parturition in cow
Relaxin → Relaxed pelvic ligaments
- Elevated tail head
- Edematous vulva
- Udder development
- “springers” → tail head ligaments relaxed (looks sprung up)
mare impending parturition
Relaxed pelvic ligaments
- Relaxed vulva
- Udder development
- “Waxed” with colostrum → dried beads of colustrum
ewe impending parturition
relaxed ligament
udder development
(shear before lactation)
presentation longitudinal
fetus spine parallel to mothers
can be anterior or posterior (head or feet first)
transverse presentation
dorsal or ventral
spine of fetus is perpendicular to mother (fetus is sidways ( back or legs first)
___ refers the relation of the fetus to the maternal pelvis
position
what do you use to orient fetus position during longitudinal presentation
dorsum (spine) of the fetus
(spine to the spine of the mother, or spine to the belly of the mother (upside down))
__ is used to determine position during transverse presentation
head
(transverse = spine perpendicular to spine of mother)
___ is the relation of the fetus extremities to the body
posture
flexed or extended
normal parturition of a horse
Anterior longitudinal presentation
- Dorso-sacral position
- Extended head and forelegs Posture
___ is the normal presentation in polytocous animals
anterior or posterior longitudinal presentation (head first or butt first)
stages of parturition
Stage I – myometrial contractions
Stage II – expulsion of fetus
Stage III – expulsion of fetal membranes and uterine involution
stage 1 of parturition
myometrial contractions (organized)
- cervical relaxation
- birth canal dilation
- fetal positioning (dorso pubic to dorso sacral position → rolls over)
- ends with chorioallantois rupture
stage II of parturition
uterine contractions
- abdominal contractions (ferguson reflex → contractions cause dilation and stretch which cause oxytocin which cause more contractions)
- passage of fetus through birth canal
stage III of partuition
expulsion of fetal membranes
• involution of uterus
Myometrial contractions continue after expulsion of the fetus and help to expel the fetal membranes. There is vasoconstriction of the arteries of the villi/microvilli and endometrium which help decrease the size of the villi and allow them to be released from the uterine crypts/ microcaruncles. There are also proteolytic enzymes that help to degrade the placental connection in cotyledonary type of placentae.
With the exception of the mare, females of the domestic animals may eat the expelled fetal membranes.
Uterine Involution
- Evacuate the uterus of any fetal fluids and fetal membranes
- Compress the uterine vasculature
- Reduce the size of the uterus
repeated release of oxytocin associated with frequent suckling. lochia discharge
amnion
feet ventrally and nose
chorion has ruptured
__ tethers the amnion to the allantosis
mesamnion - will cause amnion to rupture during birth
(not in horse)
uterine involution
cow 30-50
ewe 30 days
mare 7-10 days
sow 9-10 days
bitch 4-5 weeks
caruncle- on uterus
brown fluid/vaginal discharge → lochia
4 drugs to induce parturition
glucocorticoids- help mature fetus- surfactant
estrogens- not in food animals
PFG 2 alpha- lyses corpus luteum and forceful contraction
oxytocin- contractions
when can you induce a cow
<7-14 days before due
when can you induce a mare
>330 days pregnant
when can you induce a ewe or doe?
<5 days before due
when can you induce a sow
<3 days before due
anterior longitudinal
dorsal sacral (back of fetus against sacrum)
posture: head to right side
presentation: anterior longitudinal
position: dorsal sacral
posture: right leg and neck extended, left leg flexed at shoulder
presentation: posterior longitudinal
position: dorsal sacral
posture:
posterior longitudinal
dorsal sacral
legs flexed at the hip (breach)
dorsal transverse
R cepheloilial (head of fetus to R ilium of mare)
ventral transverse
cephilo L ilium
all limbs extended
