Therio - Bovine - Pregnancy 2

drraythe's version from 2017-09-10 01:26

Partus & Beyond

Question Answer
What’s Eutocia?Spontaneous events occurring at the end of gestation of normal length, resulting in expulsion of the fetus & its membranes, unaccompanied by any complication affecting the health, viability & future productivity of the dam or the offspring
What are the 3 stages parturition?(1) Cervical dilation
(2) Expulsion of the fetus
(3) Expulsion of the fetal membranes
When does the Preparatory Stage start? What is being prepared for? What is going on w/ the fetus during this time?Typically 3 wks prior to partus. This is the Preparation for delivery & initiation of lactation. The fetus is growing rapidly during this time
What is happening to mom during the preparatory stage?Mom is undergoing Enlargement of udder (“bagging up”) & colostogenesis (making colostrum). She has inc blood flow to the entire genital tract (looks swollen) & she has inc conc of estrogen
How do you know the mom is a few hours before calving?The vulva becomes oedematous, & the cervical plug liquefies (kinda looks like a bull string)
How does inc estrogen during the preparatory phase affect mom?Vulva increases in size, becomes soft + flabby, vaginal mucous more copious, relaxation of pelvic ligaments, gluteal muscles sink, tail head becomes elevated
What exactly triggers partus to begin?Inc levels of fetal cortisol due to stress from lack of room (since it started to grow rapidly in the preparatory phase)
How does fetal cortisol set off the chain of events which results in partus?Inc cortisol → czs inc PGF (leading to luteolysis → inc progesterone → enzymes to convert to estradiol) & also triggers enzymes to produce estradiol. The inc in PGF & estradiol leads to myometrial contractions, which inc pressure on cervix, inc Oxytocin release, which czs maximal pressure. The inc of estradiol ALSO czs inc mucus secretion which allows for more lubrication
Stage 1: Cervical dilation → explain the PASSIVE dilation (why does it happen, how does the cervix respond?)Happens due to a decrease in cervical tone (estrogen). The external os opens 1st - funnel shaped cervix
Stage 1: Cervical dilation → explain the ACTIVE dilation (how is it started/ continued?)Initiated by strong contractions of the myometrium(remember, czd by PGF & estradiol) → These force fetal membranes & parts of the fetus into partially dilated cervical canal & dilates it further → Pressure on the cervix czs Oxytocin release → myometrial contractions (& the loop begins). [Generally lasts about 2-4h in multiparous & 4-6h primiparous cows]
What is Ferguson´s reflex/Rx?Once the cervix is sufficiently dilated, the fetus enters the birth canal, it induces reflexive uterine contraction when cervix & vagina stretched. This also stimulates Ferg's reflex, which is when the uterine contractions cz Oxytocin secretion from the neurohypophysis
When in stage 1 (cervical dilation) does the moms BH change, & how?Only in the active phase does moms BH change, Then she shows abdominal discomfort, is restless, isolates herself & intermittently arches her back; cow can sniff her bedding, turn her head towards the flank or lick the flank
How do you know it is the end of stage 1 (cervical dilation)?End of 1st stage marked w/ rupture of allantochorion = “waters breaking”
Stage 2 → expulsion of the fetus: how is this stage characterized?(After stage 1 ends, marked by water breaking) Strong abdominal contraction (tenesmus) characterized by arching of the back, extension of the tail & tensing of abdominal musculature against a closed glottis. Dam also alternates btwn standing & recumbency
Which ruptures 1st-- allantoamnion or allantochorion?1st chorion, then amnion
How are fetal membranes signaled to detach, & how long does it take?After partus, a sudden decrease in blood flow due to umbilical cord rupture leads to cotyledonary shrinkage & separation from caruncles. Takes about 8h (few minutes to 12h) on average