Group 4 - Parturition and Post Party Period COMPLETE*** Flashcards
When does Parturition occur?
after the signal for birth is given by the foetus, when the foetus is sufficiently mature to survive the traumatic birthing experience
Which hormone primarily controls parturition?
foetal cortisol
What is the consequence of foetal cortisol causing a reduction in prostaglandin levels just prior to parturition?
it removes progesterones block on myometrial contractions
so the uterus can now contract
it removes progesterones block on oestradiol production
so oestradiol can stimulate increased secretions to lubricate the reproductive tract
oestradiol also increases myometrial contractions
What is the function of foetal cortisol? 2
it reduces progesterone concentration and increases oestradiol concentration
it stimulates uterine prostaglandin production
How does Foetal Cortisol achieve the switch from progesterone dominance to oestradiol dominance?
it increases the activity and expression of catalytic enzymes which convert progesterone to oestradiol
What is the consequence of foetal cortisol stimulating uterine prostaglandin production? 3
prostaglandin stimulates uterine contraction
it also acts on the ovary causing luteolysis and further reducing progesterone concentration
it stimulates the secretion of relaxin
which relaxes pelvic ligaments allowing them to stretch for cervical dilation
Explain how the foetus initially migrates towards the cervix 3
increasing concentrations of oestradiol stimulate myometrial contractions
increasing concentrations of prostaglandin stimulate myometrial contractions
this increases the pressure in the uterus and moves the foetus towards the cervix
Which reflex occurs once the Foetus applies pressure against the cervix?
- How does this reflex work? 6
neuroendocrine oxytocin reflex
the young assumes a streamline position and migrates towards the cervix
the pressure sensitive neurones in the cervix are activated when the foetus pushes against the cervix
this information is relayed to the hypothalamus
it stimulates the paraventricular nuclei
this stimulates the posterior pituitary gland to release oxytocin
oxytocin generates strong myometrial contractions
Describe the mechanism of myometrial contractions 10
each monocyte contains voltage gated calcium channels
calcium ions enter the cell through these channels
or in response to oxytocin binding to receptors on the surface
or in response to mechanical stretch as the uterus reaches its maximal size
the calcium ions bind to calmodulin inside the cell
the complex formed interacts with and activates the enzyme myosin light chain kinase
the enzyme can now convert ATP to ADP
the removed phosphate group is added to the head of the myosin light chain
this conformational change of myosin enables it to form actin-myosin cross bridges
and contract with increasing force
Which enzyme regulates myometrial contractions and how?
phosphatase can remove the phosphate group from the myosin light chain to inactivate myosin
Contractions must be highly co-ordinated in the uterus.
- Which structure enables contractions to be highly co-ordinated?
- where are they found? 2
- what do they do?
gap junctions
in clusters on the plasma membranes of myometrial cells
between individual myometrial cells
they allow the passage of ions and small molecules between cells
What is the role of oxytocin in parturition?
- how does it do this?
to increase the force, duration and frequency of contractions
via second messenger inositol triphosphate
How do prostaglandins regulate contractions? 4
isoforms of prostaglandins act locally
prostaglandin F2 alpha stimulates contractions
prostaglandin I2 stimulates relaxation
prostaglandin E2 is important for cervical softening
How does neural input regulate contractions? 4
the autonomic nervous system acts via the pelvic plexus
it innervates the uterus through specific receptors
the activation of alpha 1 receptors stimulates contraction
the activation of beta 2 receptors stimulates relaxation
As the uterus and cervix stretches, what does this do to enzyme COX2?
- What is the function of this enzyme?
- Hence, what effect does increased stretch have?
it increases the activity of COX2
to convert arachidonic acid into prostaglandins
since prostaglandins increase the number of oxytocin receptors it increases sensitivity to oxytocin
Pharmacology: Why would you want to terminate a pregnancy?
in response to unintended mating, severe risk to the dam, twin pregnancy, suspected foetal abnormality
Pharmacology: State 3 ways we can Terminate a pregnancy
induce luteolysis
remove progesterone support
induce premature parturition
Pharmacology: How can we induce luteolysis to terminate a pregnancy? 2
- How could you remove luteotrophic support in the bitch or queen?
- Why is this method variably successful?
using natural or synthetic prostaglandins
or by removing luteotrophic support
using prolactin inhibitors
success relies on the extent of reliance on the corpus luteum and timing of the lute-placental shift
Pharmacology: Aside from inducing luteolysis, how can we remove progesterone support to terminate a pregnancy? 2
by inhibiting progesterone synthesis
or inhibiting progesterone receptor action
Pharmacology: Why might you want to induce parturition? 5
reduce late calvings
ensures calving coincides with good pasture
reduces risk of foetal oversize
due to disease of dam or offspring
history of high risk pregnancy
Pharmacology: Generally, how is induced parturition achieved? 2
by mimicking normal pathways
using glucocorticoids, prostaglandins and oxytocin alone or in combination
Pharmacology: What is the risk of inducing parturition?
- when is this risk highest?
a premature foetus has reduced survival odds
for species where young develop late
Pharmacology: Why might you want to accelerate parturition? 3
due to uterine inertia
haemorrhage
retained placenta
Pharmacology: What drugs could you use to accelerate parturition?
oxytocin
prostaglandin f2 alpha agonist
glucocorticoids like dexamethasone
Pharmacology: Accelerating Parturition
- what is the risk when using Oxytocin? 2
could cause foetal death or uterine rupture if there is obstructive dystocia or if the cervix has not dilated
it could also cause unco-ordinated contractions
Pharmacology: Accelerating parturition
- What risks are associated with using prostaglandin F2 alpha to induce parturition?
could cause explosive expulsions and weak offspring
Pharmacology: When would you want to reduce or prevent contractions? 4
to delay delivery
to aid obstetrical manoeuvres
to relax the uterus for a C section
to replace a prolapsed uterus
Pharmacology: Give an example of a drug which can be used to reduce or prevent contractions
- what type of drug is this?
- What does it do?
clenbuterol
a beta 2 adrenergic agonist
it inhibits contractions and stimulates relaxation
Parturition: State the 3 stages of parturition
initiation of myometrial contractions
expulsion of foetus
expulsion of foetal membranes
Parturition: Describe the events occurring in stage 1 parturition 7
increase in foetal cortisol
increase in enzyme converting progesterone to oestradiol
progesterone concentration decreases
oestradiol concentration increase
prostaglandin concentration increases
elevated oestradiol increases tract secretions
decreasing progesterone removes the block on uterine contractions
Parturition: How does progesterone actually suppress myometrial contractions?
by increasing the expression of beta 2 adrenergic receptors
Parturition: In stage 1 of parturition, how does a foal and pup assume the disposition for expulsion? 2
- what about in a calf and lamb?
rotation from a ventral to dorsal position
extension of the forelimbs and head and neck
extension of the forelimbs and head and neck
Parturition: State some clinical signs relating to stage 1 of parturition
uterine contractions
anorexia
shivering
nesting behaviour
vulval discharge
Parturition: Stage 2
- What is the sign of onset of stage 2 from stage 1?
- How is this stimulated?
abdominal contractions
when the Fergusons reflex is initiated
as this release oxytocin
so increases the intensity and frequency of myometrial contractions
Parturition: Stage 2
- What happens when umbilical rupture occurs?
the 2 umbilical arteries and rachis retract into the abdomen to prevent haemorrhage
Parturition: Stage 2
- What happens? 10
the chorioallantois ruptures
allantoic fluid escapes the vulva
the amnion arrives at the vulva
foetal limbs appear in the amnion
the amnion may or may not rupture
as the foetus enters the birth canal it become hypoxic
this promotes foetal movement which stimulates myometrial contractions
the foetal head reaches the vulva
contractions of the uterine and abdominal muscle reach a climax
the foetus is expelled
Parturition: Stage 2
- What is the stimulus for breathing?
- What effect does lateral recumbency have on the umbilical cord?
- Why is umbilical rupture important?
the impact of air on the nostrils
the offspring will usually have an intact umbilical cord
artificial and premature rupture could deprive the newborn of a large volume of blood which normally passes from the placenta
Parturition: Stage 2
How long should it last in the following species-
cow
ewe
sow
mare
bitch
queen
1 hour
1 hour
3 hours
30 minutes
6 hours
2 hours
Parturition: Stage 2
- What position are 40% of foetuses delivered in?
caudal presentation
Parturition: Stage 3
- Describe and explain the events for passing a Cotyledonary placenta
regular abdominal contractions mostly stop after foetal expulsion
myometrial contractions decrease in amplitude but become more frequent and less regular
the lack of foetus results in vasoconstriction of arteries supplying chorionic villi
villi decrease in size and are released from the crypts
uterine contractions eventually expelled the placenta
Parturition: Stage 3
- how is passing a Diffuse placenta different? 7
- Which species does this occur in?
the apex of the chorioallantois becomes inverted
the sac is rolled down the uterine horns
the placenta is everted
when a large portion of inverted membrane forms a mass within the pelvis abdominal contractions are stimulated
the chorioallantois is expelled
the allantoic surface is outermost
the mare
Parturition: stage 3
- How long does this stage last in the mare?
- How long in the cow?
up to 1 hour
up to 6 hours
Parturition: Why is it impossible to differentiate between stages 2 and 3 in polytoccus species?
because expulsion of the placenta is interspersed between foetal births
Parturition: After stage 3, what process now needs to happen?
- What does this mean?
puerperium
the reproductive tract needs to reduce to a size similar to before pregnancy
Foetal Disposition: Which 3 ways do we describe foetal disposition?
presentation
position
posture
Foetal Disposition: Presentation
- What is meant by ‘presentation’?
- Describe the possibilities for different presentations
the relation between the longitudinal axis of the foetus and the maternal birth canal
cranial longitudinal
caudal longitudinal
dorsal transverse
ventral transverse
Foetal Disposition: Position
- What is meant by ‘position’?
- Describe different types of positions
position indicates which surface of the maternal birth canal is apposed to the vertebral column of the foetus
dorsal position
ventral position
left lateral position
right lateral position
Foetal Disposition: Posture
- Give examples of different postures
extended posture
flexed posture
Foetal Disposition: State the normal disposition
cranial longitudinal presentation
dorsal position
extended posture
Dystocia: What does Dystocia mean?
- What are some common reasons for dystocia? 4
difficult birth
foetus is too big or dam is too small
abnormal foetal disposition
multiple foetuses
poor or absent uterine contractions
Dystocia: Approach to Dystocia
- State the 3 stages in an approach to dystocia
clinical history
clinical exam
obstetrical exam
conclusion
Dystocia: Approach to Dystocia
Clinical History
- Give examples of questions to ask for the clinical history
is the foetus premature or overdue
is this her first pregnancy
give details about the sire size
what has been observed
has there been vulval discharge
have you seen uterine or abdominal contractions and when
have you observed any foetal membranes
has any fluid been expulsed?
have any foetuses been delivered
Dystocia: Approach to Dystocia
Clinical Exam
- Give some things you’d be looking at during the clinical exam
bright or dull
body condition
can she stand or walk
clinical parameters
are there foetal parts at the vulva
is there vulval discharge
what colour is the vulval discharge
Dystocia: Approach to Dystocia
- State the general principles for dealing with dystocia in increasing severity 5
conservative treatment
manipulative treatment
drug therapy
surgical treatment
euthanasia
Dystocia: Approach to Dystocia
Obstetrical Exam
- What must you do to the dam for this?
- How would you prepare for the exam?
- What things are you going to be looking and feeling for?
restrain the dam
wash the perineum and vulva
short fingernails
clean PPE
wash hands and arms
use rectal gloves
use obstetrical lubricant
is the vestibule dilated
is the cervix open
is the tract lubricated
are any foetuses present
are the present foetuses dead or alive
foetal disposition
are foetal membranes intact or detached
relative size of the birth canal to the foetus
any lacerations
Dystocia: Approach to Dystocia
- For manipulative treatment, give details of considerations to make 2
- What are the first 2 things you must do
can oxygen be given to the foetus via a nasal tube
is an epidural needed
apply lube
apply an anchoring device to any identifiable structures
Dystocia: Approach to Dystocia
- What term is given to describe correcting a presentation, position or posture?
- What does it involve? 2
mutation
pushing the foetus back into the abdomen to obtain more room
correcting the abnormal disposition
Dystocia: Approach to Dystocia
Manipulation
- Which aids can be used to provide more traction and when? 2
- When is best to provide traction?
- How should traction be applied and why?
ropes and snares when the foetus is alive
hooks can be used if the foetus is dead
during contractions
downwards towards the dams hocks to prevent damage to tissues
Dystocia: Approach to Dystocia
Manipulation
- When applying traction, what considerations should be made and why?
the orientation of the foetus as it passes through the birth canal because the largest diameter of the birth canal is at 5 past 7 on a clock
Dystocia: Approach to Dystocia
Manipulation
- Why must the foetus be delivered rapidly when in caudal presentation?
as the umbilicus will be engaging with the pelvis and could rupture before birth
Dystocia: Approach to Dystocia
After delivery, what 3 things must you check for? 4
other foetuses
lacerations or perforations
pelvic fractures
mastitis
Post Partum: What 4 things need to happen post partum
uterine involution and restoration of the endometrium
elimination of bacterial contamination
resumption of ovarian function
lactation and suckling
Post Partum: Uterine Involution
- what happens with uterine involution? 3
the uterus reduces in size
the endometrium is repaired
lochia is expulsed
Post Partum: Uterine Involution
- What happens on day 1 postpartum in a cow? 2
- What about day 4? 3
- What about day 10?
- What about day 20?
the cervix is closing
the uterus is large
the cervix is fully closed
the uterus is shrinking
lochia
follicle growth is restarting
nearly involuted
Post Partum: Uterine Involution
- Describe the mechanism for Uterine Involution 3
prostaglandin and oxytocin stimulate myometrial contractions
this sends peristaltic waves towards the cervix causing the discharge of fluid and tissue debris
co-ordinated atrophy occurs to reduce myometrial cell size
Post Partum: Uterine Involution
- What is Lochia?
- What does the second cleansing in some species consist of?
- How does this come about?
- What should the lochia smell like?
excess coracle tissue
necrosis leads to sloughing of the placentome to leave caruncle stubs
it should be odourless
Post Partum: Uterine Involution
- How long does it take in the following species -
- Beef cow
- Dairy cow
- Ewe
- Bitch
- Mare
30 days
35 days
30 days
90 days
14 days
Post Partum: Uterine Involution
The Mare has a very short uterine involution
- What is common in horses in the post partum period?
- What is this usually eliminated by?
infection
foal heat
Post Partum: Uterine Involution
- How many lochia does the Bitch have?
- What does the first one look like?
- When does the second one occur?
- what is the second one composed of?
2
green
4-6 weeks later
sloughed tissue mass
Post Partum: Elimination of Bacteria
- why do we often get bacteria inside the reproductive tract?
- How is it normally eliminated within a reasonable amount of time? 2
because the cervix is dilated during parturition
by increased myometrial contractions
by oestradiol promoting phagocytosis by leukocytes
Post Partum: Elimination of Bacteria
Sometimes bacteria in the reproductive tract can be pathological.
- What can it cause?
- What is this?
- When can we use this term to describe an infection?
- What is one major possible consequence?
endometritis
inflammation of the endometrium
for a persistent infection lasting more than 3 weeks
it is a significant cause of infertility
Post Partum: Returning to Cyclicity
- Does lactation suppress pregnancy in many species?
no
Post Partum: Returning to Cyclicity
- How do animals return to cyclicity after parturition? 4
as the corpus luteum regresses the dam enters a period of low progesterone and oestradiol
so there is limited negative feedback
so the hypothalamus is no longer being suppressed
the hypothalamus starts producing GnRH
Post Partum: Returning to Cyclicity
- If the hypothalamus starts producing GnRH very shortly after parturition, why dont they start cycling normally again for a little longer? 7
because the pituitary gland doesn’t respond to the hypothalamus for a short period of time
there is some FSH release
this enables follicles to continue to grow
the anterior pituitary becomes increasingly more sensitive to GnRH as the follicles grow
oestradiol concentration starts to increase to levels where we get positive feedback on LH
the LH surge occurs
Ovulation occurs
Post Partum: Returning to Cyclicity
- What type of oestrus do you normally get on the first oestrus after parturition?
-What else is different about the first cycle after parturition?
silent oestrus
the first cycle is generally shorter
Post Partum: Returning to Cyclicity
- In the mare, is ovarian rebound quick or slow?
- how long after parturition does it take to get foal heat?
- can pregnancy be established during foal heat?
- Why might foal heat be delayed? 2
quick
5-9 days
yes but with lower fertility rates
due to season
foal shy
Post Partum: Returning to Cyclicity
- How does a Sow return to cyclicity? 2
prolactin suppresses LH during lactation so no ovulation occurs
weaning initiates oestrus and an LH surge within 7 days
Post Partum: Returning to Cyclicity
- What happens to dogs after parturition?
- How long is this for the pregnant bitch?
- How about the non-pregnant bitch?
- What starts to happen towards the end? 3
they enter an obligatory period of anoestrus
135 days
slightly shorter
increase in oestradiol leading to suppression of FSH
new follicular wave coming
LH surge and ovulation
Post Partum: Returning to Cyclicity
Give and explain some factors which can affect ovarian rebound 4
suckling - prolactin or presence of offspring
milk yield/nutrition - causing decreased bcc or negative energy balance
periparturient abnormalities - retained foetal membranes or endometritis
seasonal - melatonin in ewes and horses
Post Partum: Returning to Cyclicity
Abnormal ovarian Rebound
- State 3 different types
delayed onset of cyclicity
cessation of ovarian activity after initial resumption
persistent corpus luteum or ovarian cysts
