Parturition and dystocia Flashcards
Describe the stage of preparation in parturition
production of relaxin (polypeptide hormone) from placenta (CL in sow)
Causes relaxation of pubic symphysis, vulval and perineal tissues
Describe the first stage of parturition - onset of uterine contractions
Fetus produces cortisol:
- cortisol enzymes convert progesteone to oestradiol
- progesterone decline removes myometrial contraction block
- increased basal uterine contractions
- elevated oestrogen increases reproductive tract secretions -> lubrication
Cortisol => increased uterine prostaglandin:
- lysis of CL
- uterine contraction due to increased PGF2a and oestrogen
- relaxin production causes degradation and remodelling of cervical matrix and cervical os opens
How do uterine contractions cause haemorrhage in species with deciduate placentas?
Placental attachments to endometrium become less intimate
Superficial cells undergo fatty degeneration
Separation of margins begins => haemorrhage
What are the signs of the first stage of parturition?
Describe the 2nd stage of parturition - expulsion of the fetus
Fergusons reflex
Allantochorion ruptures as it moves towards cervix - allantoic fluid escapes from vulva
Contractions continue, amnion appears at vulva (water bag)
Fetal limbs appear in amnion
Fetus becomes hypoxic as it enters birth canal - promotes foetal movement which stimulates myometrial contractions
Foetal head reaches vulva - climax of uterine and abdominal muscle effort
Foetus expelled
Describe the Fergusons reflex in the second stage of parturition
Fergusons reflex:
- abdominal and uterine contractions
- force fetus against cervix
- neuro-hormonal reflex
- brain release of oxytocin
- myometrial contractions
What stimulates the foetus to breath after parturition?
air hitting nostrils
What happens to the umbilical cord after parturition?
The cord ruptures after some time
Then the umbilical arteries and urachus retract into the abdomen to prevent haemorrhage
What is the risk of premature rupture of the umbilical cord?
deprive newborn of large volume of blood which would normally pass from the placenta
What happens to the amnion after/during birth?
May rupture during birth
Fetus may be delivered within the amnion and movement ruptures it
Describe the 3rd stage of parturition - expulsion of placenta
Regular abdominal contractions cease
Myometrial contractions decrease in amplitude, become less regular but become more frequent
Lack of foetus results in vasoconstriction of arteries supplying chorionic villi - villi decrease in size and release from crypts
Uterine contractions cause:
- opening of endometrial cups
- exsanguination/loss of blood from placenta
- separation of the foetal membrane
When inverted membranes form a mass in pelvis => reflex abdominal contractions
Allantochorion/placenta is expulsed
What is the puerperium
the period after expulsion of the placenta where the repro tract reduces in size to that before pregnancy
~2-8weeks
What is this foetal presentation?
Cranial longitudinal presentation
dorsal position
extended posture
What is this foetal position?
Caudal longitudinal presentation
dorsal position
extended posture
What is dystocia?
difficult birth
What are the husbandry consideration in sow parturition?
What are the signs of a ewe entering parturition?
What are the signs of a sow entering parturition?
What are the signs of a queen in parturition?
What are the signs on a bitch in parturition?
