35 - termination of preg Flashcards
indications for termination of pregnancy?
to preserve the health/well being of the dam
population control
misalliance [unwanted mating]
feeder heifers [for meat, not breeding]
termination of non viable pregnancies
what species can the “morning after” method be used to terminate pregnancy?
canine
what is the morning after Tx?
what drug and dosage?
when MUST it be given
estradiol benzoate (compounded)
0.2 mg/kg IM
given AFTER ovulation
what is the mechanism of action for estradiol benzoate?
induces embryo degeneration and delays passage from uterine tube into the uterus
side effects of estradiol benzoate?
bone marrow suppression (for high doses)
induction of p4 receptors => pyometra concern
prolongation of estrus
how effective is “morning after” estradiol benzoate if the bitch is treated after ovulation?
100% effective at preventing pregnancy
logistically, at what stage of the bitch’s cycle should you order the morning after drug if a mis mating occurs, to allow time for it to be compounded by a pharmacy?
when she is in pro estrus
that way, you have time to order it before she ovulates, to give the drug just after she ovulates
what hormones should be measured to determine if a bitch will / has ovulated?
p4
LH
how does estradiol benzoate (morning after) inc risk of pyometra?
bitch is under influence of p4 -> you treat her with e2 after ovulation -> receptors are amplified for p4 in the endometrium => inc risk for cyctic endometrial hyperplasia => pyometra
when can luteolysis be induced in the ewe?
UNTIL day 50 of pregnancy
drugs and dosages used to induce luteolysis in ewe?
2.5 mg dinoprost
125-250 ug cloprostenol
when can luteolysis be induced in the cow / heifer?
UNTIL day 150 of gestation
what drugs and dosages are used to cause luteolysis in cow?
25 mg dinoprost
500 ug chlorpostenol
according to the label, until what day of pregnancy is Lutalyse labeled effective?
until day 90
when can luteolysis be induced in sow?
after day 15, continuing through entire gestation
what drug and dose is used to induce luteolysis in sow?
10 mg dinoprost
when can luteolysis be induced in the nanny?
why?
anytime
b/c the pregnancy is CL dependent the entire pregnancy
what drug is NOT used in the hembra to induce luteolysis?
dinoprost
when can luteolysis be induced in hembra?
all gestation
what drug and dose is used for luteolysis in hembra?
250 ug of cloprostenol
when can luteolysis be induced in the mare?
until day 35 of gestation (for 1* CL)
what drugs and doses for luteolysis in mare?
5 mg dinoprost
125 ug cloprostenol
how old must the CL be in ALL SPECIES to be receptive to luteolysis?
in the sow?
all - 5 days
sow - 15 days
at what point is the bitch examined to determine if luteolysis should be induced to terminate her pregnancy?
4 weeks after mating
what is BEST method to terminate pregnancy in bitch?
spay her
why is surgical termination preferred in the bitch over medical termination?
b/c PGs have many side effects => bitch will be VERY ill
when is the best time to induce luteolysis in a bitch?
why?
over 30 days after LH surge
prior to 30 days, the CL has autonomous function and is very refractory to PGs
after 30 days, CL is easier to lyse
how long might it take to lyse the CL of the bitch?
why?
may take up to 14 days
bitch CL is very refractory to PG
why is the CL easier to lyse after 30 days?
at this time, CL is dependent on prolactin and LH so is more fragile
why is termination of pregnancy in bitch not performed NOT immediately after the mis mating?
b/c 60% will not be pregnant
wait 4 weeks to see if she is pregnant
after 45 days in the bitch pregnancy, how must the pregnancy be terminated?
remove uterus and inject each puppy thru the uterine wall with euthanasia solution
what are 2 protocols for use of dinoprost to cause luteolytsis in the bitch?
which is used and why?
ONE:
- 05 mg/kg BID for one day
- 1 mg/kg BID for one day
- 25 mg/kg BID until empty, so typically for 5 days or more
TWO:
0.01 mg/kg QID
OPTION 1 is used b/c low dose option is NOT effective
in addition to dinoprost, what else may be used in the bitch?
why is it not used?
0.005 mg/kg cloprostenol BID until empty - typically 7 days or more
a dog died in one study - so if you use it and the bitch dies, the lawyers will use this against you
when selecting between dinoprost and clorprostenol, which is the better option for the bitch?
why?
dinoprost
d/t its ecbolic effects
what class of drugs can be combined with PG for luteolysis in the bitch?
dopaminergic drugs
what drug used commonly in Europe for bitch abortion is NOT legal in the USA?
why not?
RU-486
human abortion drug
what is mechanism of RU-486?
competitive p4 receptor blocker
removes the effect of p4 on the endometrium to induce fetal death
how to induce luteolysis in the feline?
at what time in gestation?
0.1 mg/kg PG BIT for 5-7 days
after day 40
t/f
once the feline placenta has begun producing p4, the PG is no longer effective at causing abortion
false
is effective after placenta begins producing p4
after day 100, what drugs are used to cause luteolysis in cow?
PgF and dexamethosone
t/f
prednisolone may be used instead of dexamathasone in the cow for luteolysis
false
prednisolone may NOT be used
why is dexamethosone used in cow to induce luteolysis after 100 days?
stimulates pre partal fetal distress
b/c fetal adrenal gland is well developed enough to respond
how is dexamethasone administered in the cow and what amount?
25 mg IM
what is used to induce parturition in the ewe after day 50?
drug, amount and route of administration
dexamethosone
10 mg (can use up to 15 mg)
IM
why is PgF NOT effective at causing luteolysis in the ewe after day 50?
she no longer has a CL at this point
how long does the hembra rely on CL for maintenance of preg?
entire gestation
11 mos
what is used to end hembra pregnancy?
dexamethasone
t/f
the hembra CL is refractory to luteolysis, like the dog
clinical significance?
false
it is VERY sensitive - to corticosteroids so it is easy to abort on accident
clin sig: topical Tx for derm conditions and drops for ophthalmic conditions may induce abortion in the hembra
why must multiple doses of PgF be given to the mare between days 35-80 to cause luteylysis?
b/c she has accessory CLs by this time so needs multiple doses to lyse them all
after what day will the mare have delayed return to estrus?
why?
after day 35
b/c endometrial cups have formed and they cannot be destroyed
what must be done after day 80 in mare gestation to abort medically?
how is this accomplished?
side affects?
destroy fetal placental source of p4
multiple high doses of dexamethasone
mare may develop laminitis -> avoid using this Tx
prior to day 35, what how can preg be terminated in the mare?
crush the conceptus
give dose of PG
after day 80, how is abortion achieved in the mare surgically?
manual abortion
u/s guided needle puncture to kill conceptus / fetus
dilate cervix and remove fetus (may be alive - so must kill it after)
what is used to dilate cervix of mare for manual abortion?
PgE2 or PgE1 (misoprostol)
