Post-partum period

Question 1

Describe the post-partum period

Answer 1

Uterine involution (+ restoration of endometrium)
Elimination of bacterial contamination from repro tract
Resumption of ovarian function
Lactation/suckling

Question 2

What is uterine involution?

Answer 2

Reduction in uterine size and involves:
- endometrial repair
- expulsion of lochia/foetal fluids
- restoring uterus so pregnancy can be re-established

Question 3

Describe the cow anatomy 1 day post-partum

Answer 3

Cervix closing
large uterus
haemorrhaging on vaginal wall

Question 4

Describe the cow anatomy 4 days post-partum

Answer 4

Shrinking uterus
lochia (foetal fluids) in vagina
cervix closed

Question 5

What is the gravid horn?

Answer 5

The uterine horn which held the pregnancy

Question 6

Describe cow anatomy 10 days post-partum

Answer 6

Follicular growth re-starting
Lochia disappeared
Heomarrhaging repaired

Question 7

Describe the mechanism of uterus involution

Answer 7

Myometrial contractions:
- stimulated by oxytocin and PGF2a
- peristaltic waves towards cervix
- discharge of fluid/tissue debris
- compress vasculature
Co-ordinated atrophy:
- Myometrium stretch during pregnancy
- reduction in myometrial cell size

Question 8

What stimulates oxytocin release post-partum?

Answer 8

Suckling

Question 9

What is the effect of oxytocin post-partum?

Answer 9

milk production
myometrial contractions -> uterus involution

Question 10

What is lochia?

Answer 10

Uterine discharge
‘second cleansing’
Remnants of foetal placenta and endometrial tissue
Odourless (bad odour = problem)
Blood-tinged

Question 11

Describe the process of endometrial repair

Answer 11

Restoration of caruncle:
- necrosis => sloughing of placentome
- leaves caruncular stubs
Inter-caruncular endometrium:
- thins during pregnancy
- undergoes tissue remodelling post-partum
- new epithelial coverage

Question 12

Why does uterine repair take longer in dairy cows?

Answer 12

Calves removed so no suckling => lower oxytocin levels

Question 13

Why is uterine involution very quick in the mare?

Answer 13

Hastened by foal heat:
- comes into oestrus shortly after parturition
- release of oestradiol with heat aids involution
Small lochia
Little endometrial disruption
Normal by day 14

Question 14

Why is uterine involution slow in the bitch?

Answer 14

2 lochia:
- 1st: from pigmented zone in placenta (green)
- 2nd: normal lochia, 4-6 weeks later
Endometrial repair:
- slow (3 months)
- multiple remodelling steps
Back to normal in 90 days

Question 15

What normal processes aid the elimination of bacterial contamination during pregnancy?

Answer 15

Help eliminate by myometrial contraction
Phagocytosis by leukocytes (promoted by oestradiol/oestrus)

Question 16

What conditions can pre-dispose the uterus to bacterial contamination in the peri- and post-partum period

Answer 16

Dystocia - human beings introducing bacteria, traumatic, cesarian etc.
Dead foetus
Dirty environment at parturition
Prolapse
Uterine inertia
Retained foetal membranes
Metabolic stress due to lactation

Question 17

Describe the pathology of endometritis/’whites’

Answer 17

Persistent infection:
- reduced uterine defence mechanism
- devitalised tissue e.g., retained foetal membranes
Inflammation of endometrium
Opportunistic pathogens
Cause of infertility

Question 18

Describe the cause of anoestrus during gestation

Answer 18

Prolonged, high progesterone:
- suppression of HPO axis
- folliclular waves but fewer and no ovulation (except in mares - endometrial cups)
- occasional oestrus behaviour

Question 19

Describe the cause of anoestrus after parturition

Answer 19

Limited number of antral follicles
CL from pregnancy regressing
Period of low progesterone and low oestradiol
Limited -ve feedback

Question 20

Describe the mechanism of ovarian rebound

Answer 20

Re-initiation of HPO axis:
- pituitary is refractory/unresponsive to GnRH
- FSH secretion initiated due to lack of -ve feedback
- antral follicular wave emerges
Resumption of ovarian activity:
- increasing sensitivity of gonadotropes to GnRH leads to:
- increased FSH stimulation of oestradiol production
- increased LH pulse frequency
- first ovulation (silent oestrus)
- short first oestrus cycle

Question 21

Describe ovarian rebound in the sow

Answer 21

Profound suckling effects:
- early follicular activity
- but prolactin suppresses LH => no ovulation
Return to oestrus:
- weaning iniates oestrus and LH surge

Question 22

Describe ovarian rebound in the dog

Answer 22

In late anoestrus:
- FSH high
- follicular waves re-appear (influenced by dopamine)
- enables synchrony of HPO axis
- enter follicular phase as wave of oestradiol suppresses FSH

Question 23

Describe ovarian rebound in cats

Answer 23

Oestrus inhibited by lactation (not uniform)
Variable period of anoestrus post-weaning
Early weaning can cause early oestrus

Question 24

What influences ovarian rebound?

Answer 24

Suckling (prolactin)
Milk yield/nutrition - decreasing body condition and negative energy balance delays rebound
Peri-parturient abnormalities - retained foetal membranes, endometritis
Seasonal - e.g., melatonin in the ewe

Question 25

How can negative energy balance lead to ovarian pathologies

Answer 25

Question 26

Describe abnormal ovarian rebound

Answer 26

Delayed onset of cyclicity
Cessation of ovarian activity
Ovarian pathologies:
- follicular/luteal cysts
- persistent CL