Termination of Pregnancy and Induction of Parturition Flashcards
what does approach to termination depend on
-Some species are CL‐dependent for the whole pregnancy, meaning NO contribution from the placenta
How well does PGF2a work to induce abortion in Cows?
highly effective until 150d, and then again after 250d into gestation
Efficiency of pregnancy termination using cortisol ‐ cow
doesn’t work before 150d, works well after 250d
what is dexamethasone
cortisol
Efficiency of pregnancy termination – Combination ‐ cow
when you give dexamethasone and PGF2a together, its fully effective throughout the entire gestation
causes for abortion in mares
-Wrong sire
-Unintentional breeding
-Twins
-Problem pregnancy (Hydrops, Prepubic tendon rupture)
how to induce abortion in mare <28d
Pinch one vesicle transrectally (twins)
how to induce abortion in mare <35d
PGF2α
before cups form and produce eCG
how to induce abortion in mare 35 – 120 days
PGF2α – twice daily for 3‐5 days +/‐ manual extraction
(when cups are present)
how to induce abortion in mare > 120 days
-PGF2α – twice daily for 3‐5 days, then oxytocin to expel fetus +/‐ assist and extract
-Fetus usually born alive
how to induce abortion in sheep before 50-60d
In sheep, one injection of PGF2a is 90% effective in inducing abortion before 50‐60 days; two injections 48 hours apart ‐ is 100% effective
how to induce abortion in sheep after 50-60d
After 50‐60 days corticosteroid is somewhat effective – may require
multiple injections and manual dilation/extraction
induction of abortion in goats
PGF2a is effective at any stage of pregnancy
induction of abortion in pigs
PGF2a is effective at any stage of pregnancy
how many PGF2a injections are recommended for induction of abortion and why
-2 PGF2a injections is recommended to ensure complete luteolysis
-Reduced risk of fetal mummification
-Increases success rate
what was the leading cause of abortion in mares before U/S
twinning
what is twinning usually due to
Usually due to double ovulation
how do you prevent twinning going to term
-Routine early diagnosis by ultrasound at
when is it best to pinch a twin?
-Best performed at 14‐17 days (before fixation)
-Can still be done up to approx. day 28
-Manual crushing per‐rectum
Management of Twin Pregnancy in
Mares (unilateral vs bilateral)
-Depends on whether the embryonic vesicles are in the same horn (unilateral) or separate horns (bilateral)
-If unilateral, >85% chance that by day 60 the pregnancy will reduce to a singleton or no pregnancy, on its own (natural reduction)
-If bilateral, highly likely to continue as twins until abortion in late gestation
twin reduction in the mare; Day 28 – 55
-Ultrasound monitored disruption
-good for bilateral cases
twin reduction in the mare; Day 70 – 120
Craniocervical dislocation
-Rectally
-Colpotomy (vaginal incision)
-Flank incision
twin reduction in the mare; Day 90 – 180
Transabdominal ultrasound‐guided
puncture
-Intra‐fetal injection of procaine penicillin
-The later performed, the greater the risk of placental insufficiency and abortion of pregnancy
twin pregnancies in cows; why its selected for, what its associated with
-Selection for increased milk production = more double ovulations; also higher use of synchronization programs
-Associated with higher embryo/pregnancy losses
-92% of cows dx with singleton will calve vs. 76% of cows dx with twins (as low as 54% in some studies)
-Higher rates of dystocia and postpartum disease
-Risk of Freemartin Syndrome in calves
-Manual rupture of one sac at
reasons for induction of parturition (4)
-Illness in the dam
-Ensuring assistance at delivery
-High risk pregnancies
-Owner convenience
Physiology of parturition in cows (hormones)
-Declining progesterone
-Increasing estrogen
what is a high risk when you induce parturition
-Very high incidence of retained placenta
what drugs can you give to induce parturition in cows
-Dexamethasone and Prostaglandin combination. Most predictable
-Within 2 weeks of calving
-Calving about 36 hours after administration
-With Dex only = about 43‐52 hrs
-With PGF only = 45‐72 hrs
Induction of parturition in ovine
-Corticosteroid – 80% lamb in 42 hrs (avg)
-PGF not effective
Induction of parturition in caprine
-PGF2α >140 days – kidding in 30‐50 hrs
Induction of parturition in porcine
-PGF2α day 111 + oxytocin 24 hrs later; farrow in ~ 6 hrs
Guidelines for Safe Induction in mares (4)
- Min 330 days gestation
- Udder development + colostrum
- Relaxation of sacrosciatic ligaments and vulva
- Electrolyte analysis of colostrum indicates fetal maturity
when does fetal maturation happen in horses
last 2 days of gestation
how do Electrolyte changes in milk indicate fetal maturity
-Increase in Calcium (Ca2+) to >400 ppm, or >200 ppm (10 mmol/ml) on two consecutive days, indicates fetal maturity
-Potassium should be greater than Sodium
-Decrease in Sodium to <35 mmol/ml
-Increase in Potassium to > 80 mmol/ml
pH of Mare’s Milk Determines Fetal
Readiness for Birth
-Using standard pH strips, milk can be tested to determine fetal readiness
-When pH drops below 6.4 = foaling within 24 hours
what should you always avoid when inducing parturition in mares
PGF2α
-NOT reliable (remember, no CL’s are present after 120 days in mares)
-NOT recommended
what can you use to induce parturition in a mare
Oxytocin
-10‐15 IU, IV, repeat every 15‐20 min
-Usually foal within 60 min (after 2nd or 3rd injection)
what is another option for inducing parturition last case scenario?
Corticosteroids
-Only cross equine placenta if very high doses given repeatedly
-Foal approximately 8 days later
-Appears safe between 315 and 325 days gestation to induce fetal maturation
risks of using corticosteroids to induce parturition in mares
-Risk of laminitis
-No colostrum
-If used close to term leads to dystocia and fetal death in high %
what are mares incredibly sensitive to in late pregnancy
-Mares are exquisitely sensitive to oxytocin in late pregnancy even if fetus is not mature
-Potential to induce too early and have a dead foal!!
time to baby if you give PGF2α + Dex in cows
36h
time to baby if you give Dex in ewes
42h
time to baby if you give PGF2α in does
30-50h
time to baby if you give PGF2α +
Oxytocin ( in 24hrs) in pigs
6h
time to baby if you give Low dose Oxytocin in horses
<1h
