51. Phases, processes and influencing factors of involution in cattle

Question 1

Involution?

Answer 1

Involution

• 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 Involution?

Answer 2

Stages of the involution

• Early:

o from calving until GnRH sensitivity of the hypophysis

o first dominant follicle: 10 to 14 days

• Middle:

o until the first ovulation (usually 1 to 2 follicular waves)

o approx. day 21

• Finishing:

o uterine involution is complete (uterine horns and cervix have a diameter of max. 4 cm)

o Re-epithelisation of the caruncles is complete

o approx. day 42 but high deviations (beef cattle – shorter, dairy – usually longer)

Question 3

Processes of the involution?

Answer 3

Processes of the involution

• Four processes simultaneously:

o uterine involution (decrease in size)

o regeneration of the endometrium

o return of cyclicity in the ovaries

o elimination of bacterial contamination

Question 4

Uterine involution?

Answer 4

1. Uterine involution

• Myometrial contractions after calving due to high oxytocin concentration – compression of blood vessels,

bleeding decreases

• 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 caruncles

o (Foetal membranes – see RFM)

Duration:

• size of the uterus decreases by half by day 5
• complete involution: 3 weeks (from approx. 10 to 13 kg to 1 kg)

Involution of the cervix:

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

Question 5

Regeneration of the endometrium?

Answer 5

2. Regeneration of the endometrium:

• After the detachment of the allantochorion, the caruncles undergo desquamation.
• Regeneration of the area of the caruncles begins at the edges 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 6

Return to cyclicity in the ovaries?

Answer 6

Return to cyclicity in the ovaries:

• pregnancy – high P4 concentration – no ovulation
• calving – P4 decr – GnRH incr - FSH incr - follicular waves begin – dominant follicle
• Fate of the dominant follicle:

o LH pulse frequency low (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 – anoestrus – delayed involution

Question 7

Elimination of the bacterial contamination?

Answer 7

4. Elimination of bacterial contamination (uterine clearance):
   • During pregnancy the uterine lumen is sterile (?).
   • After calving the uterus is colonised by numerous bacterial species through the open cervix.
   • Neutrophil granulocytes, cytokines, 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 8

Factors influencing the involution?

Answer 8

Factors influencing the involution

1. Negative energy balance – NEB:

• dry matter intake!!
• NEB: energy deficit - lipomobilisation – blood NEFA (non-esterified fatty acids incr)- liver oxidation capacity

decr - NEFA oxidation incomplete – ketone bodies (BHB!!)

• Effects of NEB

o NEB causes lower LH pulse frequency

§ Delayed first ovulation

o Ketone bodies

§ Immune response decr, regeneration delayed

• NEB can last 8-12 weeks post-partum

Question 9

Blood calcium concentration?

Answer 9

. Blood calcium concentration:

• subclinical hypocalcaemia (73%) or milk fever (1%)
• Effects of hypocalcaemia:

o Ca is needed for uterine contractions:

§ slower detachment of foetal membranes– RFM

§ decrease of uterus size is slower– delayed involution

• immune response decr
• NEB incr

Question 10

Retention of the foetal membranes(RFM)?

Answer 10

Retention of the foetal membranes (RFM):

• The allantochorion is attached to the maternal side at the areas of the caruncles (placentoma). They are

disconnected by chemical and physical changes due to uterine contraction and loss of blood supply (the

caruncle itself DOES NOT CONTAIN muscle tissue!).

• Expulsion of the foetal membranes: max. 24 hours (12 to 24 hours) – after that – RFM
• Causes:

o polyfactorial

• RFM increases risk of puerperal metritis – delayed involution!

Clinical signs:

• general clinical signs are rare
• foetal membrane visible or can be found by rectal/vaginal palpation

Question 11

Treatment of traditional/modern ?

Answer 11

Treatment:

o Traditional:

§ Manual removal of the foetal membranes (carefully!!), combined with dry uterine treatment

(uterine tablet – Tetra-bol 2000 – oxytetracycline) + oxytocin, BUT! bacterial complications

§ NO UTERINE FLUSHING

o Modern:

§ Tying up or partially cutting the foetal membranes if they hang from the vulva, treating the

original problem, oxytocin administration

§ NO VAGINAL INSERTION OF ANY KIND! – bacterial contamination and complications decr

§ if general clinical signs – systemic AB (cephalosporins, e.g., ceftiofur (Naxcel inj.)) and NSAIDs

(ketoprofen or meloxicam)