Equine - Pregnancy and Twin Management Flashcards
If a mare is not pregnant, _____ will be secreted, ____ will occur, and the mare will ______ to ______.
prostaglandin, luteolysis, return estrus
What signal causes the CL to persist in a pregnant mare?
MRP signal
When does the embryo enter the uterine lumen?
5-6 days post-ovulation
How would you characterize the movement of the embryo around the uterus?
passive
What structure forms during embryonic movement?
the embryonic capsule
What day during embryonic movement is critical for MRP?
day 14-16
By when is the embryo fixated?
day 16-18
What are some non-specific pregnancy indicators?
No return to estrus, visual assessment, vaginal speculum examination, milk/serum progesterone assay, equine chorionic gonadotropin detection, and estrogen detection
What is assessed via visual assessment/abdominal ballottement when determining pregnancy?
Pear shaped abdomen by 5-6 months, direct ballottement, fetal movement observation, fetal drop in a ventral position
When would vaginal speculum examination be done to determine pregnancy? Is it recommended?
18-21 days post ovulation - not recommended
What would the cervix look like on vaginal speculum examination if a mare was pregnant?
Dry, pale white, tightly closed, with external os protruding into the center of the cranial vagina
When would a milk/serum progesterone assay be done and what would a result greater than 4 ng/ml indicate?
18-20 days post ovulation - would imply presence of a functioning CL
What is equine chorionic gonadotropin produced by?
endometrial cups
When is ECG produced?
40-120 days in gestation
When is it best to detect for higher than normal estrogen levels?
60-240 days of pregnancy
Are any of the non-specific pregnancy indicators reliable?
no
What are some specific pregnancy indicators?
transrectal palpation and transrectal ultrasound
When is transrectal palpation performed?
20 days or later post ovulation
What can be detected if a mare is pregnant on transrectal palpation?
toned uterus and cervix, pronounced ovarian follicular activity, and swelling at the base of the horn (ping pong size early on)
At 20-30 days post ovulation, what can be found on trans-rectal palpation?
prominent uterine and cervical tone and bulge swelling on the antero-ventral base of the horn
What size will the bulge be at 35-40 days post ovulation?
about tennis ball sized
What size will the bulge be at 45-50 days post ovulation?
softball sized
What size will the bulge be at 60-65 days post ovulation?
football sized
What size will the bulge be at 100-120 days post ovulation?
basketball or volleyball sized
What can be felt on transrectal palpation at 150-210 days post ovulation?
enlarged uterus - difficult to feel the fetus and structures
What can be palpated 240+ days post ovulation?
a fetus to some extent
What is the gold standard for pregnancy detection in a mare?
transrectal ultrasound
When is visualization of the fetus poor?
from 3-6 months of gestation
What can be detected via transrectal ultrasound?
diagnosis of pregnancy, viability of the fetus, twin detection, vesicle growth measurement, and late term placental health
How early can transrectal ultrasound detect a pregnancy?
less than 10 days post ovulation; it is 99% accurate at 15 days
When can fetal sex be determined via transrectal ultrasound?
at approximately 60-70 days gestation
When will the embryonic vesicle be visable on ultrasound and what will it look like?
10 days post ovulation - very round vesicles with hyperechoic poles
What will the embryonic vesicle look like at 18-20 days post ovulation?
a guitar pick
When is the embryo proper visable via ultrasound?
21 days post ovulation
What percent of the embryo proper is the allantois at 25-26 days?
25%
What percent of the embryo proper is the allantois at 28-30 days?
50%
What percent of the embryo proper is the allantois at 34-36 days?
75%
What percent of the embryo proper is the allantois at 38-40 days?
100%
Where will the embryo proper be located at 21 days post ovulation?
ventral
Where will the embryo proper be located at 38 days post ovulation?
dorsal
Where will the embryo proper be located at 45-50 days post ovulation?
ventral
When can the embryo heartbeat be detected on ultrasound?
26-28 days post ovulation
What type of placenta does the horse have?
epithelialchorial, microcotyledonary
When does placental attachment begin? When does full attachment happen by?
40-45 days; 150 days for full attachment
What is the process of forming endometrial cups?
An annular band of trophoblast forms a chorionic girdle at allantois and regressing yolk sac. The chorionic girdle cells invade the endothelium and form the cups
When do endometrial cups disappear?
120-130 days
What do the endometrial cups secrete?
ECG/PMSG
What does ECG/PMSG do?
It has LH-like activity that allows for an accessory CL, it is luteotropic to the ovulatory CL, and it bridges a gap between ovulatory CL and fetoplacental unit progestin production (5 alpha pregnane)
What do 5 alpha pregnanes do?
They help maintain the pregnancy from when the initial CL comes until the placenta can take over in producing progestins
What is the leading cause of abortions in the mare?
twins
If diagnosed with twins, ______% will abort late term?
65-70%
What complications are associated with twins if the mare goes to term?
dystocias, RFM, delayed uterine involution, metritis, damage to the reproductive tract, immaturity to foals, expense, and mortality
In regards to timing in ovulation, what can lead to twinning?
synchronous and asynchronous ovulations
Most ovulations that result in twins are ________.
Dizygotic (2 ovulations)
What is unilateral fixation of twins?
they fix in the same horns
What is bilateral fixation of twins?
they fix in their own horn
What breeds are twins common in?
thoroughbreds and drafts
How can resolution of twins be done?
benign neglect, manual reduction, trans-vaginal aspiration/injection, cranio-cervical dislocation, transcutaneous aspiration/injection, elective abortion
If benign neglect is chosen to reduce twins, even though it is not recommended, which fixation will have the best outcome?
unilateral fixation - the mare will spontaneously reduce to singleton 75% of the time by 40 days
What is manual reduction of twins?
crushing the vesicle manually
When should manual reduction be done?
prior to fixation
How is manual reduction done?
The vesciles are separated as much as possible, the smaller vesicle is crushed, and you want to manually crush it at the tip of the horn if possible. Additional therapy can be applied such as NSAIDs when necessary.
How successful is manual reduction if done at the tip of the horn?
90% successful
If both vesicles are lost during manual reduction, when will the mare return to fertile estrus?
1-2 weeks
When would trans-vaginal aspiration/injection be done?
If the twins were diagnosed after fixation (days 18-40)
Note: additional therapy can be provided such as NSAIDs and Regumate
Why can’t you do trans-vaginal aspiration/injection after 40 days?
there is too much fluid
When would cranio-cervial dislocation be done?
at 60-110 days of gestation
What are the approaches to cranio-cervial dislocation and which should be done first?
trans-rectal (first) and trans-abdominal
What exactly is cranio-cervical dislocation/how is it done?
It is the manual fracturing of the first cervical vertebra from the cranium to rupture the spinal cord - there is a distinctive pop
Again, additional therapy can be provided to the mare
If you notice a heartbeat after performing a cranio-cervical dislocation, does that mean the twin is still alive/viable?
no - the heartbeat can still be recorded for a couple of days
When is transcutaneous aspiration/injection done?
if the pregnancy was diagnosed after 100 days (day 100 -130)
How is transcutaneous aspiration/injection done?
It is a standing procedure where you inject intracardiac solution that will kill the fetus
Guess what… you can give NSAIDs and Regumate for additional therapy
How is elective abortion performed?
by injecting the mare with prostaglandin or PGE to induce abortion
What is the protocol for using prostaglandin in elective abortions and when would you do it?
You give multiple doses - once daily for 4-7 days
It is typically used if the other options have failed and sometimes it does not always work
What does PGE do to induce abortion?
with the combination of cervical dilation it disrupts the fetal membranes - you may need a uterine lavage, if you do you will need to recheck
