17 – Puerperium and Lactation Flashcards
1
Q
Puerperium
A
- Period after parturition characterized by reproductive tract returning to the non-pregnant state to enable the female to become pregnant again
o Uterine involution
2
Q
Involution
A
- Actual physical process of uterus returning to the normal non-pregnant size and function
3
Q
Lactation
A
- Process of synthesis, secretion and removal of milk from mammary gland
4
Q
When do puerperium and lactation start?
A
- Immediately after parturition
- Simultaneous for a short period
5
Q
Puerperium starts and ends
A
- Starts: right after parturition
- Ends: restoration of reproductive function
6
Q
Four major events of puerperium
A
- Myometrial contractions and ejection of lochia
- Endometrial repair
- Resumption of ovarian function
- Elimination of bacterial contamination of reproductive tract
7
Q
Why is short puerperium desirable?
A
- To increase the eligibility for a subsequent pregnancy
- Ex. dairy cows: frequent pregnancies max lifetime max yield
- *select for animals or use dry-off period
8
Q
Right after parturition, myometrium undergoes strong repeated contractions
A
- Short, high frequency for 2-3 days
- Helps discharge fluids
- Aids tissue debris removal
- Compresses vasculature in uterine wall to minimize hemorrhage
- Reduces overall size of uterus
9
Q
What are the contractions of the myometrium driven by?
A
- Suckling
- Oxytocin secretion
10
Q
Rapid atrophy of uterus so mass is reduced to
A
- Non-pregnant size
o Individual muscle cells decrease to 70% in size - Differences in pregnancies (primiparous vs. multiparous)
o Ex. ‘recover’ faster if never been pregnant - Timing of contractile inhibition depends on species
11
Q
What happens during and after myometrial contractions?
A
- Lochia is expelled from vulva
12
Q
Lochia
A
- Fluid containing blood, necrotic tissue and mucous
- Discharge begins 1-2 days post-partum (dairy)
- Highest volumes in first 10days in dairy cows (then decreases substantially)
13
Q
Equine lochia
A
- Relatively low amount
- Usually stops 24-48hr after foaling
14
Q
Pig lochia
A
- Discharge observed for up to 48hr post-farrowing
15
Q
Dog lochia
A
- Discharge immediately after parturition can be green
- Changes to bloody mucoid discharge within 12hr
16
Q
Cat lochia
A
- Obvious vulvar discharge for up to a week after kittening
- Complete by 2 weeks
17
Q
What can discharges past normal periods indicate?
A
- Infection
- Metritis (inflammation of whole uterus)
- Endometritis
- *needs to be treated
18
Q
Ruminant endometrial repair
A
- Once fetal cotyledons separate from maternal caruncles, VASOCONSTRICTION occurs followed by NECROSIS
- Endometrial crypts contain fragments of chorionic villi, necrosis begins 48hr post-partum (necrotic septal mass)
- Day 5: necrosis with neutrophils and lochia discharge
- Sloughing (of necrotic septal mass) complete by 15-19 days
- **Re-epithelization occurs by 25-30 days
19
Q
Equine endometrial repair
A
- Less repair required due to different placentation
- 1d post-partum some degeneration of endometrial glands and inflammatory cells (d5)
- Regeneration complete in 10 days
20
Q
Pig endometrial repair
A
- Very small amount of degeneration compared to ruminants
- Epithelial cells transition from columnar to FLATTENED degenerated cells by 7d PP
- Active cell division until endometrium regeneration by 21d PP = ready for new pregnancy
21
Q
Dog endometrial repair
A
- Areas of previous placental attachment (zonary) requires more regeneration time
- Complete by 12 weeks
22
Q
Cat endometrial repair
A
- More rapid than dog
- Complete by 25-30days
23
Q
Inhibitory levels of steroids is lost with birth
A
- FSH levels can build again
- First PP ovulation is frequently associated with ABSENCE of estrus behaviour
- *similarity in characteristics between initial cyclicity with onset of puberty AND return to cyclicity in PP animals
24
Q
Portion of cows cycling and PP
A
- Increases by days PP
- *early initiation of ovarian cyclicity before breeding leads to better fertility
25
Return to cyclicity ruminants: follicular wave emergence
- Growing follicles, dominant then preovulatory follicles produce estrogen
- High estrogen: induces estrous behaviours
- With ovulation and CL formation=progesterone production increases and primes uterus for future
26
Equine return to cyclicity
- Rapid
- 5-12 days PP
- Follicular activity as early as 2d PP
27
Small ruminants (ex. sheep) return to cyclicity
- Seasonal=cycle at next breeding season after anestrus period
28
Pig return to cyclicity
- Suckling and weaning have PROUFOUND effect on rebound
- Later the time of weaning=shorter the interval to first estrous
29
Cat return to cyclicity
- Lactation can suppress estrous
- If no kittens=can return to estrous 7-10d PP
30
Dog return to cyclicity
- Return to estrous unpredictable
- Parturition followed by anestrous
31
Elimination of bacterial contamination
- Uterus is not sterile during pregnancy
o Contains commensal and NON-pathogenic organisms at low levels
- Microbiome can shift though PP
o Excessive imbalance can lead to disease (ex. endometritis)
- *Elevated estradiol can induce immune responses to maintain balance
32
Bacterial contamination of uterus is due to
- Relaxation of physical barriers
- Ex. open cervix for delivery
o Repeated contractions enhance bacterial contamination via vacuum effect
o Lochia presence can promote additional bacterial growth
33
What clears out bacterial invaders of uterus?
- Uterine defence mechanisms
- *also related to ENDOMETRIAL REGENERATION
- Clearance by 5-7weeks PP 9cows
34
When does the final mammary develop in the dam occur?
- During pregnancy
o Alveoli grow into bunches or lobules
o Group of lobules connects into duct and is now a LOBE
o End of pregnancy=lobulo-alveolar structures are 90% of gland
35
What hormones stimulate milk synthesis?
- Prolactin
- Placental lactogen
- Adrenal cortical hormones
36
Milk secretion
- Synthesized and secreted by alveolar cells into alveolar lumen
o Prolactin: maintains milk production
o Suckling stimulates release from anterior pituitary
- Suckling signal, inhibits dopaminergic neurons in hypothalamus=now prolactin can be produced by A. pituitary
37
Milk ejection
- Active movement of milk from alveoli and alveolar ducts into larger ducts, cisterns and teats
o Removed by suckling newborn
- *neuroendocrine reflex
38
Milk ejection requires:
- Sensory activation (auditory, tactile, visual)
- Neural activation of hypothalamus
- Oxytocin (from P. pituitary) release into blood
- Contraction of myoepithelial cells
- Mechanical transfer of milk form alveoli into ducts and eventually teat
39
Mammary involution
- Process where mammary alveolar cells STOP producing milk and reorganize back to non-pregnant state
40
What happens as milk need decreases in neonates? (mammary gland involution)
- Pressure atrophy or buildup pressure within gland (still producing some milk) INHIBITS function of alveoli
o Cells atrophy
o Lymphocytes, macrophages INVADE tissue and help remodelling
