Post-partum period

what are the 3 stages of parturition

1. initiation of myometrial contractions

2. expulsion of foetus

3. expulsion of foetal membranes

Briefly describe what takes place in the first stage of parturition

1. foetus initiates via stress

2. PGF2a produced

3. cervix dilates and foetus enters cervix

4. OT simulated myometrial contractions

state 3 things that take place in stage 2 of parturition

1. OT stimulates myometrial contractions

2. foetal movements

3. rupture of membranes

state 3 things that take place in third stage of parturition

1. foetal membranes expelled

2. chorionic villi dislodged from maternal

3. vasoconstriction

what is uterine involution?

• reduction in uterine size

what are 3 things uterine involution involves?

1. endometrial repair

2. expulsion of lochia

3. restoring uterus so that pregnancy can be restablished

what are lochia?

• foetal fluid

does the uterus return back to it’s exact size, do we know this?

• no, and it’s very difficult to assess - likely similar to milk production, that the original size isn’t ever truly reached again

what will we expect to happen by day 1 post parturition

• cervix closes but still able to manipulate it

• large uterus - horns indistinguishable

• prominent corpora lutea/corpus luteum

what do we expect the uterus to look like on day 4 postpartum

• shrinking uterus with LH and RH of uterus identifiable

• lochia accumulating

• cervix tighter but still able to put a finger in, with vaginal haemorrhaging present (due to trauma of parturition)

what should the uterus look like at day 10 postpartum?

• follicular growth restarting

• gravid and non-gravid horn identifiable

• cervix back to normal

by what day do we expect the uterus to be relatively back to normal in a cow?

• day 20

what mechanisms are involved in uterus involution? (2)

1. myometrial involution

2. co-ordinated atrophy

how do myometrial contractions help with the uterus involuting?

• causes discharge of lochia and compresses vasculature

what coordinated atrophy takes place to aid with uterus involution?

• myometrium was stretched during pregnancy, now there’s a reduction in myometrial cell size → uterus involution

Describe lochia

• blood-tinged fluid containing remnants of foetal placenta and endometrial tissue

• up to 1.5L of odourless fluid

is lochia normal?

• yes

what changes to the caruncle take place post partum?

• sloughing of the placentome due to necrosis, leaving caruncular ‘‘stubs’’ which then repair

What is this image demonstrating?

• the process of the resotration of the caruncle post parturition

when is uterine repair complete for a beef cow

• 30d

when is uterine repair complete for a dairy cow

• 35-45d

when is uterine repair complete for a bitch

• 90d

when is uterine repair complete for a ewe

• 30d

when is uterine repair complete for a mare

• 14d

when is uterine repair complete for a queen

• 30d

when is uterine repair complete for a sow

• 28-30d

when does a beef cow start having overian activity again after parturition?

• 50-60d

when does a dairy cow start having overian activity again after parturition?

• 18-25d

why do beef cows have earlier uterine repair compared to dairy cows?

• due to having the calf to suckle it promotes uterine involution more quickly than in dairy cows

when does a dog start having overian activity again after parturition?

• 135d

when does a ewe start having overian activity again after parturition?

• 180d

when does a mare start having overian activity again after parturition?

• 5-12d

when does a queenstart having overian activity again after parturition?

• variable

when does a sowstart having overian activity again after parturition?

• 5-7d from weaning

why do ewes start resuming ovarian activity so late?

• due to being seasonal short day breeders, after lambing in spring they enter their natural period of anoestrus

why is uterine involution in the mare so rapid?

• foal heat → increased oestradiol

• small lochia

• little endometrial disruption due to type of placenta

is infection post partum common?

• yes, but should be eliminated quickly

describe the lochia of a mare

• dark brown, usually odourless

• should cease after 1-2 days

how many lochia does a female dog have

• 2

what are the 2 lochia of the female dog?

1. immediate and green due to zonary placenta

2. 4-6 weeks layer due to sloughing of tissue mass

how long should the first lochia of a uterus last in a dog?

• 1-3d

what hsould the 1st lochia of a dog look like

• immediate should be green followed by red, watery then mucoid appearance for D1-3

how long does endometrial repair take in the dog?

• around 3 months due to multiple tissue remodelling steps

how does the endometrial repair/remodelling compare in a pregnant to non-pregnant dog?

• shorter in the non-pregnant dog

why do we expect bacterial contamination of the uterus during parturition?

• cervix is dilated - uterus is exposed

• non-sterile process

should we be concerned about bacterial contamination of the uterus?

• no, as long as it’s eliminated within a reasonable time e.g. via myometrial contractions

what are 3 conditions which pre-dispose the uterus to bacterial contamination post-partum?

1. parturition difficulties

2. retained foetal membranes

3. severe negative E balance

what effect oculd bacterial infection have long term?

• subsequent reduced fertility, delayed return to cyclicity and reduced conception rates

what is the most common post partum pathology

• endometritis = whites

how do we describe endometritis?

• a persistent infection >3 weeks causing inflammation of the endometrium

state 2 reasons why endometritis may persist post parturition

1. attenuated uterine defence mechanism

2. devitalised tissue - retained foetal membranes

what is key to recognise about the different changes that take place after parturition, as demonstrated by this schematic?

• they’re not independently occurring, they all overlap

why does ovarian inactivity continue after parturition?

• CL from pregnancy regresses → low P4

• only a few antral follicles present → but less -ve feedback due to low P4 → increased FSH stimulation and E2 production

• lH pulse frequency increases → first ovulation

take a while!

what can we refer to the first ovulation after parturition as?

• silent oestrus

do mares have rapid ovarian rebound?

• yea, rapid onset detectible within 2 days post parturition!

As mares have rapid ovarian rebound, do they always demonstrate oestrus behaviour straight away?

• no, they can suppress the behaviour, potentially due to the foal being at foot

can mares establish pregnancy in the first ovulation that is detectable after parturition?

• yes but fertility rates are lower

why are fertility rates lower in the mare during the first ovulation post parturition?

• as the uterus is still enlarged, which means it’s unable to have a pregnancy established in it

why don’t sows return to oestrus after parturition?

• suckling has profound effects on prolactin release which suppresses LH

why do sows return to oestrus so quickly after weaning?

• loss of inhibition by prolactin stimulates oestrus and LH surge in 7 days

do dogs return to cyclicity after pregnancy?

• NO - obligatory anoestrous which isn’t lactational

describe the hormonal changes that take place in the dog in late anoestrus

1. FSH is high due to no feedback

2. follicular waves reappear

3. HPO axis synchronicity

what strongly influences return to oestrus in dogs

• nutrition and condition

what drug can we use to speed up return to cyclicity in the dog?

• dopamine agonists

Is oestrus inhibited by lactation?

• yes in many species but not in all of them

with lactation, what will hasten onset of oestrus?

• early weaning

state 4 thinggs that affect ovarian rebound

1. suckling

2. milk yield/nutrition

3. peri-parturient abnormalities

4. seasonal

how does a negative energy balance affect ovarian rebound?

1. less gonadotrophin secretion

2. poor follicle growth and oestradiol production

3. poor oestrus and inadequate LH surge follow

4. pathological ovary (due to inadequate LH)

in which species does prolactin NOT have an effect in?

• cows

state 2 peri-parturient abnormalities that affect ovarian rebound

1. retained foetal membranes

2. endometritis

what are 3 clinically relevant occurrences as a result of abnormal ovarian rebound

1. delayed onset of cyclicity

2. cessation of ovarian activity

3. ovarian pathologies

What does this schematic represent?

• ovarian rebound in the ‘‘ideal’’ cow

What does this P4 profile represent?

• delayed 1st oestrus after parturition

What does this P4 graph represent?

• cessation of ovarian activity after initial resumption

What does this graph represent?

• persistent corpora lutea