Pregnancy
We
often think of pregnancy as a delicate and fragile
condition. When it comes to horses, this perception
is perhaps due to the mare's relatively poor reproductive
performance in comparison to other domestic animals.
However, in a natural setting, the mare does comparatively
well reproductively. Therefore, this seemingly
poor performance is due as much to improper management
as to any reproductive deficiency. Fortunately,
management is something we can control.
The
earliest days of an embryo's existence are perhaps
the most precarious. During the first 30 days,
there is a 10-15% chance that the embryo will
be resorbed. Stress, illness, uterine infection,
hormonal abnormalities, the presence of twins,
and other factors have been implicated in early
embryonic loss. Often, the cause remains undetermined. |
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When
the mare conceives, the fertilized egg (zygote)
travels down the fallopian tubes and enters the
uterus around day 6-7. It migrates throughout
the uterus until about day 16 and typically implants
into the uterine wall at 6-8 weeks. By day 12-13,
the embryonic vesicle is usually large enough
to be detected by ultrasonic examinations, during
which an image is made by bouncing sound waves
off tissues. Ultrasound checks are extremely important
at 14 t- 16 day checks. This is the first day
you can make sure the mare is no in foal with
twins. If possible the vet will pinch off one
of the follicles and will check again at day 28
to make sure all is well with the remaining follicle.
Neither
teasing, palpation, nor ultrasound has been shown
to harm the developing embryo or endanger the
pregnancy. However, because of the embryo's uncertain
beginning. This is one reason the early checks
are so important as it allows you to breed again
if she did not settle in foal. |
