Therio- Bovine- Pregnancy 2

wilsbach's version from 2015-11-04 18:32

partus and beyond

Question Answer
what's Eutocia?spontaneous events occurring at the end of gestation of normal length, resulting in expulsion of the foetus and its membranes, unaccompanied by any complication affecting the health, viability and future productivity of the dam or the offspring
what are the 3 stages parturition?(1) cervical dilation (2) Expulsion of the foetus (3) Expulsion of the foetal membranes
when does the Preparatory Stage start? what is being prepared for? what is going on with the fetus during this time?Typically 3 wks prior to partus, This is the Preparation for delivery and 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”) and colostogenesis (making colostrum). she has inc blood flow to the entire genital tract (looks swollen) and she has inc conc of estrogen
how do you know the mom is a few hours before calving?the vulva becomes oedematous, and the cervical plug liquifies (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--> causes inc PGF(leading to luteolysis-->inc progesterone-->enzymes to convert to estradiol) and also triggers enzymes to produce estradiol. The inc in PGF and estrdiol leads to myometrial contractions, which inc pressure on cervix, inc oxytocin release, which causes maximal pressure. The inc of estradiol ALSO causes inc mucus secretion which allows for more lubrication (see slide 81)
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 first - funnel shaped cervix
Stage 1: Cervical dilation--> explain the ACTIVE dilation (how is it started/ continued?)Initiated by strong contractions of the myometrium(remember, caused by PGF and estradiol)--> These force foetal membranes and parts of the foetus into partially dilated cervical canal and dilates it further-->Pressure on the cervix causes oxytocin release -> myometrial contractions (anddd the loop begins). [generally lasts about 2-4h in multiparous and 4-6h primiparous cows]
what is Ferguson´s reflex/reaction?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 cause oxytocin secretion from the neurohypophysis
when in stage one (cervical dilation) does the moms bh change, and how?only in the active phase does moms bh change, Then she shows abdominal discomfort, is restless, isolates herself and 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 first stage marked with rupture of allantochorion= “waters breaking”
Stage 2--> expulsion of the fetus: how is this stage charaterized?(after stage one ends, marked by water breaking) strong abdominal contraction (tenesmus) characterised by arching of the back, extension of the tail and tensing of abdominal musculature against a closed glottis. Dam also alternates between standing and recumbency
which ruptures first-- allantoamnion or allantochorion?first chorion, then amnion
how are fetal membranes signaled to detach, and how long does it take?After partus, a sudden decrease in blood flow due to umbilical cord rupture leads to cotyledonary shrinkage and separation from caruncles. Takes about 8h (few minutes to 12h) on average