Phases, processes and influencing factors of involution in cattle

Question 1

Involution

Answer 1

• the recovery of the reproductive tract
• the dam will be able to maintain another pregnancy.
• the period after calving is also called the puerperium

Question 2

Stages of the involution

Answer 2

1. Early:
   • from calving until GnRH sensitivity of the hypophysis
   • first dominant follicle: 10 to 14 days
2. Middle:
   • until the first ovulation (usually 1 to 2 follicular waves)
   • approx. day 21
3. Finishing:
   • uterine involution is complete (uterine horns and cervix have a diameter of max. 4 cm)
   • Re-epithelisation of the caruncules is complete
   • approx. day 42 but high deviations (beef cattle – shorter, dairy – usually longer)

Question 3

Processes of the involution

Answer 3

1. uterine involution (decrease in size)
2. regeneration of the endometrium
3. return of cyclicity in the ovaries
4. elimination of bacterial contamination

Question 4

Processes of the involution

Uterine involution

Answer 4

• Myometrial contractions after calving due to high oxytocin concentration – compression of blood vessels, bleeding ↓
• Uterine content after calving:
o lochia (initially yellowish-brown, later reddish, viscous discharge containing blood
and tissue debris, but with no unpleasant smell):
▪ amniotic (allantoic) fluid
▪ blood
▪ parts of the detaching caruncules
o (fetalmembranes–seeRFM)

Question 5

Processes of the involution

Uterine involution

Duration

Answer 5

• size of the uterus decreases by half by day 5

* complete involution: 3 weeks (from approx. 10 to 13 kg to 1 kg)

Question 6

Processes of the involution

Uterine involution

Involution of the cervix

Answer 6

• fast decrease in diameter (24 hours – hand barely fits through, 4 days – two fingers fit)
• complete involution: about 30 days

Question 7

Processes of the involution

Regeneration of the endometrium

Answer 7

• After the detachment of the allantochorion, the caruncules undergo desquamation.
• Regeneration of the area of the caruncules begins at the egdes and proceeds inward.
• Complete regeneration of the epithelium is achieved around day 25.
• Regeneration of the deeper layers can last up to 8 weeks.

Question 8

Processes of the involution

Return to cyclicity in the ovaries

Answer 8

• pregnancy – high P4 concentration – no ovulation
• calving – P4 ↓ – GnRH ↑ - FSH ↑ - follicular waves begin – dominant follicle
• Fate of the dominant follicle:
o LHpulsefrequencylow(1):atresia
o LH pulse frequency low (2): anovulatory (folliculus theca) cyst
o LH pulse frequency normal: ovulation – corpus luteum (CL) (cycle might be shorter)
• First ovulation: approx. day 21
• BUT! dairy cow: high milk yield, NEB (cause of low LH pulse frequency) – time of first
ovulation can be delayed by several weeks – anestrus – delayedinvolution

Question 9

Processes of the involution

Elimination of bacterial contamination (uterine clearance)

Answer 9

• During pregnancy the uterine lumen is sterile (?).
• After calving the uterus is colonised by numerous bacterial species through the open cervix.
• Neutrophil granulocytes, cytokins, etc. – elimination of contamination –but! recolonisation
• Uterine flora can change multiple times during the involution.
• Majority of the bacteria involved are not pathogenic.
• Uterine immune response and success of elimination of the contamination is influenced by
several factors: NEB, Ca2+, RFM, …

Question 10

Factors influencing the involution

Answer 10

Negative energy balance – NEB
Blood calcium concentration
Retention of the fetal membranes (RFM)

Question 11

Factors influencing the involution

Negative energy balance – NEB:

Answer 11

• dry matter intake!!
• NEB: energy deficit - lipomobilisation – blood NEFA (non-esterified fatty acids) ↑ - liver
oxidation capacity↓ - NEFA oxidation incomplete – ketone bodies (BHB!!)
• Effects of NEB:
o NEB causes lower LH pulse frequency – delayed first ovulation
o ketone bodies: immune response ↓, regeneration delayed • NEB can last 8 to 12 weeks post partum

Question 12

Factors influencing the involution

Blood calcium concentration

Answer 12

• subclinical hypocalcaemia (73%) or milk fever (1%)
• Effects of hypocalcaemia:
o Ca is needed for uterine contractions:
▪ slower detachment of fetal membranes– RFM
▪ decrease of uterus size is slower– delayed involution
o immune response ↓
o NEB↑

Question 13

Factors influencing the involution

Retention of the fetal membranes (RFM)

Answer 13

• The allantochorion is attached to the maternal side at the areas of the caruncules (placentoma). They are disconnected by chemical and physical changes due to uterine contraction and loss of blood supply (the caruncule itself DOES NOT CONTAIN muscle tissue!).
• Expulsion of the fetal membranes: max. 24 hours (12 to 24 hours) – after that – RFM
• Causes: polyfactorial
• RFM increases risk of puerperal metritis – delayed involution!

Question 14

Factors influencing the involution

Retention of the fetal membranes (RFM)

Clinical signs

Answer 14

• general clinical signs are rare

* fetal membrane visible or can be found by rectal/vaginal palpation

Question 15

Factors influencing the involution

Retention of the fetal membranes (RFM)

Traditional treatment

Answer 15

o manual removal of the fetal membranes (carefully!!), combined with dry uterine
treatment (uterine tablet –Tetra-bol 2000 –oxytetraciyclin) + oxytocin, BUT!
bacterial complications
o NO UTERINE FLUSHING

Question 16

Factors influencing the involution

Retention of the fetal membranes (RFM)

Modern treatment

Answer 16

o tying up or partially cutting the fetal membranes if they hang from the vulva, treating
the original problem, oxytocinadministration
o NO VAGINAL INSERTION OF ANY KIND! – bacterial contamination and
complications ↓
o if general clinical signs – systemic AB (cephalosporins, e.g. ceftiofur (Naxcel inj.))
and NSAIDs (ketoprofen or meloxicam)