27 - Parturition and Puerperium Flashcards
Three stages of parturition**
- Initiation of myometrial contractions (removal of “P4 block” caused by fetal signaling)
- Expulsion of the fetus (strong contractions of myometrium)
- Expulsion of fetal membranes
Hormones involved in pregnancy (8)
- early pregnancy factor (EPF)
- progesterone
- equine chorionic gonadotropin (eCG)
- adrenal corticotropin (ACTH)
- estrogens
- prostaglandin F2a
- relaxin
- oxytocin
Which pregnancy hormones are related to parturition
- ACTH
- estrogens
- PGF2a
- relaxin
-oxytocin
Describe the release of adrenal corticotropin and its function
As fetal mass approaches the space limitations of uterus, fetus is brought under stress = anterior pituitary will secrete ACTH.
ACTH stimulates the fetal adrenal gland to produce the corticosteroid cortisol
Fetal cortisol passes into maternal circulation and abolishes the P4 block
Slide 8, 9
How does cortisol abolish the P4 block
- Promotes conversion of P4 to E2
- Promotes PGF2a synthesis by the placenta
Effects of estradiol on the female tract
- increases secretions of cervix and vagina (mucus for lubrication)
- stimulates contractions of the myometrium (pushes fetus into cervical canal)
Role of PGF2a in parturition? What stimulates it
Cortisol stimulates placenta to produce PGF2a
- initiates regression of CL (reducing P4 production & helping eliminate P4 block)
- stimulates a surge of relaxin
What is relaxin? Role?
Peptide hormone produced by the CL and/or the placenta during gestation
Softens connective tissue of the cervix and promotes elasticity of pelvic ligaments (prepares birth canal for fetus expulsion)
Relaxin production site based on species
CL and placenta: mare, ewe, sow, queen
CL only: cow
Placenta only: rabbit
What is oxytocin? Secreted by? Role in parturition?
Neuropeptide secreted by posterior pit
- pressure on the cervix from the fetus activates pressure sensitive neurons that signal the PP to release oxytocin
- oxytocin augments the myometrial contractions initiated by E2 to a level that allows for expulsion of the fetus and eventually the fetal membranes
Slide 13
Slide 14***
Diff hormones/stages of parturition
Duration of stages 1, 2 and 3 in cow, ewe, mare, sow, bitch
Cow:
2-6h
30-60 mins
6-12 hours
Ewe:
2-6h
30-120 mins
5-8h
Mare:
1-4h
12-30 mins
1h
Sow:
2-12 h
150-180 mins
1-4h
Bitch:
6-12h
6h
Pass w neonate
Slide 15
What is dystocia?
Difficult or abnormal birthing process resulting in a extended duration of parturition
Can result in serious consequences for the fetus and dam
Potential causes of dysotica
- fetal size (too big)
- dam condition (fat or skinny)
- improper fetal positioning (breech, turned)
- multiple births in monotocous species (cows, mares)
Normal fetal presentation in cattle/horses? Possible abnormal ones?
Normal= cranial longitudinal
Problematic=
left dorso-ilial
caudal longitudinal
dorso-pubic
transverse dorsal
transverse ventral
Slides 17-20
