Induction of Parturition and Termination of
Pregnancy
Dr. Aijaz Ali Channa
Assistant Professor, Theriogenology, UVAS
Cell # 0300-4894463
Indications
Therapeutic abortion may be indicated during
normal or abnormal pregnancy in the cow
Misidentification of a breeding female
Accidental breeding of a very young heifer, and unwanted pregnancy
in feedlot heifers are indications for abortion during normal gestation
treatment protocols for pathologic conditions of pregnancy
including fetal maceration, fetal mummification
Hydro-amnion , and hydro-allantois.
PHYSIOLOGY OF PREGNANCY MAINTENANCE
Gestation in the cow extends 270 to 292 days after breeding.
Once conception has occurred, progesterone is essential for pregnancy maintenance
Although the maternal endocrine events of the first 15 days of cycle and of pregnancy
are similar, interferon-γ, results in maternal recognition of pregnancy by inhibition of
luteolysis and prolonged CL life.
progesterone levels fluctuate between 6 and 15ng/mL throughout gestation, with a
gradual decline in the 2 to 4 weeks preceding parturition.
Pregnant cows that undergo ovariectomy before the first 3 to 5 months of gestation
will abort. In cows ovariectomized after 200 days of gestation, progesterone secretion
is maintained, although at significantly lower levels than before ovariectomy.These
cows do not abort.
Progesterone level dependence
Progesterone is luteal in origin for the first 150 days of gestation.
Between 150 and 250 days the placenta acts as additional source of progesterone.
In the final month of gestation, placental progesterone declines and pregnancy is
again dependent on luteal progesterone.
Successful treatment to induce abortion must lower circulating progesterone below
1ng/mL, which is the threshold necessary to maintain pregnancy.
MECHANISM OF ACTION OF THERAPEUTIC AGENTS
Prostaglandin F2 Alpha:
The CL is sensitive to PGF2α beginning 5 to 7 days after
ovulation.
In both normal and abnormal pregnancy,
administration of PGF2α after that time
results in luteolysis at any stage of
pregnancy
PGF2α treatment alone induces abortion only
up to 5 months of gestation.
Glucocorticoids
Glucocorticoid treatment appears to
reduce placental progesterone
secretion from 150 days of gestation.
Short acting dexamethasone 20-30 mg/animal will induce parturition
within 70 hours
Luteal progesterone is unaffected, however, and abortion does not result
from glucocorticoid treatment until the last month of gestation.
During the final month of gestation, glucocorticoids act at the
fetoplacental unit to increase the production of estradiol and PGF2α,
resulting in induced parturition.
A combination of PGF2α and glucocorticoids will induce abortion from 150
days of gestation.
Estrogens
Treatment with estrogens during
the first 2 to 3 days after ovulation alters
oviductal transport of the bovine embryo
and terminates pregnancy.
After the development of the CL, estrogens cause luteolysis by inducing the
endogenous PGF2α luteolytic cascade from the endometrium
The endometrium must be intact for estrogens to induce abortion. Estrogen is
an exogenous luteolysin with unknown effects on the fetoplacental unit;
therefore, abortion can be induced reliably at up to 150 days of gestation.
Treatment of cows between 200 and 220 days of gestation with 30 mg estradiol
valerate, alone or in combination with dexamethasone, has not been shown to
decrease serum progesterone or result in abortion.
Oxytocin
Treatment of cows with oxytocin from days 2 to 7 after estrus with 100 to 200 IU of
oxytocin prevents pregnancy , probably by preventing normal luteal development.
TREATMENT STRATEGIES IN TERMINATING PREGNANCY
Normal Pregnancy up to 150 Days:
In the first 5 months of pregnancy, the treatment of choice is PGF2α.
Cows do not respond until 5 to 7 days after ovulation.
After that time, a majority of cows respond by returning to estrus within 3 to 5 days of
treatment.
Treatment with oxytocin in the first few days after ovulation may prevent the establishment of
pregnancy.
Between days 5 and 10 after ovulation, intrauterine infusion of irritating solutions prevents the
establishment of pregnancy and may cause luteolysis and early return to estrus.
Infusion later than 11 days after ovulation occasionally lengthens the estrous cycle.
Suitable solutions include 0.5% percent aqueous iodine(20-40 ml) and 2g tetracycline in
saline.
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Estrogens administered within 72 hours of ovulation impede oviductal transit of
embryos.
Up to 5 months of gestation, administration of an estradiol ester, such as
estradiol valerate, results in abortion within 7 days ,Occasional abortions occur
up to 14 days after treatment.
Estradiol should be administered every 4 days until abortion.
Abortion was reported in 60% to 80% of heifers within 7 days of a single
treatment
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Manual enucleation of the CL by transrectal manipulation removes progesterone support
for pregnancy and results in abortion at up to 150 days.
Manual rupture of the amniotic vesicle by transrectal manipulation is possible once the
vesicle can be palpated at 30 to 35 days of gestation.
After 60 days and up to 120 days of gestation, when the amniotic vesicle can no longer
be isolated within the fluid-filled chorioallantois.
it may be possible to terminate pregnancy by manual decapitation of the fetus.
The mean time to abortion is 25 days, but abortion may occur up to 8 weeks after
treatment
Disadvantages:
Technique may induce adhesions of the ovary and ovarian bursa and, occasionally, severe
hemorrhage.
Abortion after 150 Days of Normal Pregnancy
Between 5 and 8 months of gestation, a combination of PGF2α and
dexamethasone is necessary to remove both luteal and extra ovarian sources of
progesterone
Abortion will occur within 5 days.
In the final month of pregnancy, either dexamethasone or prostaglandin alone
induces premature parturition within 2 to 3 days.
SEQUELS TO INDUCED ABORTION
Induced abortion after the fourth month of gestation results in an approximately
80% incidence of retained fetal membranes
Fetal mummification develops in 2% to 4% of pregnant feedlot heifers treated with
a combination of PGF2α and dexamethasone.
In occasional cows, metritis or pyometra will develop after induced abortion.
acute toxic metritis is an unusual sequel.
Thanks
Induction of abortion and parturition in Ewe and Goat
Physiology of Pregnancy
Gestation length in ewes ranges from 144 to 149days.
Early pregnancy is maintained by the corpus luteum which is protected
from luteolysis by a number of proteins, including ovine trophoblastic
protein 1 which is produced by the fetus.
From 60 days' gestation until parturition, maintenance of ovine
pregnancy is dependent on placental progesterone.
Induction of abortion
PGF2α < 50 days Dinoprost 15 mg Cloprostenol 100 µgm
PGF2α + Dexamethasone (20 mg) > 50 days but may have to use once/day for 2
to 3 days Variable success
Strategies to Induce lambing
1. Corticosteroids
2. Oxytocin
3. Oestrogen
4. Anti-progesterone drugs
Corticosteroids
Dexamethlasone at a dose of 16 mg
betamethasone at dose of 10mg
flumethasone at a dose of 2-5 mg
These drugs induce parturition 42 + 7 hours
Oxytocin:
Oxytocin causes myometrial contractions only if oxytocin receptors are present. It
can therefore be used to speed up parturition in ewe in which the birth process has
started, is about to start, or which has been induced by corticosteroids.
Oestrogen
Oestrogen therapy has been used with some success to induce parturition in sheep.
A dose of 2 mg of oestradiol benzoate given by intramuscular injection has been
Shown to induce parturition in 50 per cent of ewes treated on day 142 of pregnancy
Anti-progesterone drugs
Anti-progesterone drugs, such as epostane which suppress
progesterone
synthesis has been used at a dose of 50 mg to induce parturition
in 100 percent of ewes treated within 10 days of term (Silver
1987). The drug can be given by intramuscular or intravenous
injection
GOATS
Induction of abortion
PGF2 α - At any stage of gestation: abortion in 50 to 72 hrs
Induction of parturition
Glucocorticoids 15-20 mg dexamethasone Within 7 to 10 days of expected kidding
Prostaglandins Last 5 to 6 days of pregnancy. After day 142, will kid 42 to 72 hrs later
Induction of abortion and parturition in Mare
Methods of Termination
Intrauterine infusion of NS 50 ml in early days
Estradiol valerate 3-5 mg
Prostaglandin(fluprostinol) 250-1000 ug IM
Oxytocin 20 iu in early days
Methods of induction
1st of all determine fetal maturity then there are several methods that may be
employed to induce parturition
1. Corticosteroids
2. Prostaglandins
3. Oxytocin
Corticosteroids
dexamethasone, a corticosteroid administer daily for 4 days from
day 321 of gestation.
Parturition is reported to occur within 1 week
Prostaglandins
Fluprostenol , 250–1000 ug administer intramuscularly
parturition within 2 hr
The mare will show the initial signs of parturition (stage 1) within 30 min.
Oxytocin
most commonly used today to induce parturition
low levels of oxytocin, 20 iu, have been used, administered over time
(3 h) and this results in parturition within 1 h
Oestrogen can be used in combination with oxytocin as an induction
regime and is reported to aid cervical dilatation and hence ease the
process of parturition
Termination of pregnancy in Bitches
Estrogen .044 mg IM once or .1-1mg PO for 5 days in early days
prostaglandin (cloprostinole 2.5ug/kg SC three times a day after 48 hour or
1ug/kg with cabergoline
Glucocorticoids (dexamethasone 5mg twice for 10 days or 0.1-0.2 mg orally)
cause fetal death in 5-13 days and expulsion in 7-15 days
• Prolactin inhibitor Oral administration of Bromocriptine (parlodel, a human drug)
at varying doses ranging from 10 to 100 µg/kg/day for 10 to 14 days.
• Cabergoline at a dose of 5 µg/kg/day for 5 to 10 days, given orally.
