Termination of Pregnancy Flashcards
What are the three types of pregnancy termination
1) abortion
2) induction of parturition
3) twin reduction
What are some indications for induction of abortion in cows?
- feedlot heifer
- incorrect sire
- heifers too young
- bull/colt/ram/buck got loose
Approach to pregnancy determination depends on what
whether the animal is CL dependent for the entire pregnancy or not
What animal species maintain the CL throughout gestation
cows
pigs
dogs
cats
goats
what animal species do not have progesterone contribution from the placenta
dogs
cats
pigs
goats
what is the contribution of the CL and placenta to progesterone production in sheep (ovine)
CL: <50-60d
Placenta: >50-60d
what is the contribution of the CL and placenta to progesterone production in horses
CL (endometrial cups): 120-150d
Placenta: >70d
when does the placenta start producing progesterone in cows
150-250d
what plays an important role in initiation of parturition and what is a caveat
fetal glucocorticoids, only if the feto-placental unit is alive and functioning
when can you induce abortion using PGF2a in cows
<150 d or >250d (when the placenta is not contributing to progesterone levels)
when can you induce abortion using dexamethasone in cows? when is it 100% effective?
starts to work at 150d (low efficacy) and becomes 100% after 250d
if you wanted to be 100% certain you can induce abortion in a cow and you don’t know what day of gestation, what can you use
both PGF2a (lyse the CL) and dexamethasone (stops placental secretion)
T/F you only need 1 injection of PGF2a if inducing abortion in a cow <150 or >250d of gestation
F; give 2 to ensure you induce complete luteolysis
what happens if you did not completely lyse the CL in a gestating cow using PGF2α
mummification
in cases of fetal mummification or maceration in cows, how do you induce abortion
PGF2a -> luteolysis -> drop in progesterone
what are indications for induction of abortion in horses?
1) wrong sire
2) unintentional breeding
3) twins
4) problem pregnancy (ex. hydrops, PPT rupture)
In the horse, what is significant:
- in the first 35 days
- at day 35
- between 35-120 days
- after 120 days
- in the first 35 days: only CL
- at day 35: endometrial cups formed
- between 35-120 days: eCG from endometrial cups -> acts like LH -> secondary CL formed -> progesterone
- after 120 days: only placental source of progesterone
how do we induce abortion in mares:
- <28 days of pregnancy:
- <35 days of pregnancy:
- 35-120 days of pregnancy:
- >120 days of pregnancy:
- <28 days: pinch one vesicle transrectally (in case of twins)
- <35 days: PGF2a
- 35-120 days: PGF2a twice daily for 3-5 days, may need manual extraction
- > 120 days: PGF2α twice daily for 3-5 days, oxytocin, assist and extract (usually need to euthanize fetus once born)
How do we induce abortion in sheep vs goats
in goats, only the CL is the source of progesterone, so 2 PGF2a injections can be given at any stage of gestation
in sheep, <50-60 days you can give 2 shots of PGF2a since only the CL is present; after 50-60 days you can give multiple injections of corticosteroids and manually dilate/extract
in pigs, how do we induce abortion
2 shots of PGF2a at any stage of gestation
what are the concerns with twinning in mares
- leading cause of abortion before ultrasound
- rarely go to term due to placental insufficiency
- severe damage to the mare, and usually neither fetus survives
T/F twinning in the mare can be unilateral or bilateral
T
how can you tell whether twins in a mare ovulated at the same time or not
if they are the same size or different sizes on ultrasound
when and how is manual twin reduction performed in the name
best at 14-17 days (before fixation) but can be done up to day 28; manually crush per rectum by massaging up the horn and popping
what is the difference in management of twin pregnancy if unilateral vs bilateral pregnancy in the mare
if unilateral: >85% chance that natural reduction will occur and the twins will reduce to a singleton or no pregnancy
if bilateral: very likely to continue as twins until abortion in late gestation
how can we reduce twins in the mare:
- between days 28-55
- between days 70-120
- between days 90-180
days 28-55: ultrasound monitored disruption
days 70-120: craniocervical dislocation (rectally, by colpotomy or by flank incision)
days 90-180: transabdominal ultrasound guided injection of procaine penicillin
is the twinning rate in cows going up or down and why
up; selection for higher production, more double ovulations, synchronization programs
what are the 3 main issues with twinning in cows
- freemartins
- higher embryo/pregnancy loss
- associated with dystocia and postpartum disease
how can we reduce twins in cows
manual rupture between days 35-40
what are some indications for initiation of parturition
1) disease in dam
2) ensuring assistance at delivery
3) high risk pregnancy
4) owner convenience?
the physiology of parturition is characterized by declining ______________ and rising _________________
progesterone; estrogen
what is the most common combination used to initiate parturition in cows? when can this be done? how soon after do they calve? what is an issue?
dexamethasone and PGF2α; last 2 weeks of pregnancy; 36h; retained placenta
the earlier that calving is initiated:
- what effect of mortality?
- what effect on value?
- what effect on sales?
- higher mortality
- less value
- fewer sales
how do we induce parturition in:
- ovine
- caprine
- porcine
- ovine: corticosteroid (PGF2a not effective)
- caprine: PGF2a (>140d)
- porcine: PGF2a (>111d) and oxytocin 24h later
how soon after initiating parturition will the following species give birth:
- ovine
- caprine
- porcine
- ovine: 42h
- caprine: 30-50h
- porcine: 6h
what concerns are unique about initiating parturition in mares?
the fetus matures in the last 2 days of gestation, and horses have a wide range of normal gestation lengths
what are the guidelines for safe induction of parturition in mares? (4)
1) minimum 330 days
2) udder development and colostrum present
3) relaxation of sacrosciatic ligaments and vulva
4) analysis of colostrum indicates fetal maturity
what are the electrolytes changes we want to observe in a mare before initiating parturition
1) increase in calcium to >400ppm or >200ppm for 2 consecutive days
2) potassium greater than sodium (sodium <35 mmol/ml, potassium >80 mmol/ml)
T/F the pH of the mares milk determines fetal readiness for birth
T
when the mares milk pH drops below _____, you can expect them to foal within the next _____
6.4; 24h
what is the fastest and best way to induce parturition in the mare?
a) PGF2a
b) oxytocin
c) corticosteroids
b) oxytocin
how do you induce parturition with oxytocin
IV injection (10-15 IU) every 15-20 minutes; usually foal within 60min
can corticosteroids be used to initiate parturition in the mare? what is a problem with this method?
yes, but will foal in 8 DAYS, no colostrum, risk of laminitis, can lead to dystocia and fetal death
T/F mares are incredibly sensitive to oxytocin in late pregnancy and will foal even if fetus is not mature
T
