Gestation averages about 336 days. For a
due date count back 25 days. If she was last bred on April 26, she's
due on April 1. This could vary by 20 days early or late.
Supposedly, research has shown that 70% of all mares may repeat
their first pregnancy cycle regardless of whether it is a filly or
colt. If you know the number of days of her gestation in previous
pregnancies, you can check that number against this pregnancy to see
how close she is to repeating her cycle each year.
Keeping a record of each mare's pregnancies is thus helpful.
You really need to be present when
your mare has her baby. I believe you owe this to her. So many
babies don't make it because the owners were not present. They get
stuck (dystocia) or suffocate in
an unbroken sac. Many miniatures go early, so after day 300, we try
to watch our mares very closely. Having cameras on her stall really
aid in the monitoring process, as does
milk strip testing.
The mare's eggs can "float" for up to 2
weeks before it implants in the uterine lining. Thus there is a
larger window of gestation for horses.
We did have a fun thread on our
AZminiatures yahoo group wherein one breeder told of a mare that
went 384 days and another mare who waited 372 days. Those have got
to be record long for gestation times. On the short end, one
miniature breeder told of a baby born at 296 days with only peach
fuzz, no hair and cartilage for legs. The vet told this lady she
would die, but love and determination (along with lots of hours) has
grown this baby up to be 4 years old now. They had to be there every
2 hours around the clock and support her while she nursed. After 2
weeks, she was getting up on her own! As you can see, there can be a
great amount of variation.
There are urine tests you can buy to preg
check your mare. Checking can also be done via a blood test or
ultrasound.
We narrow down our foaling dates by
looking at all
the signs of foaling
and by using milk strips!
Click here to learn about milk strips!
I have been told by a few different vets
that mares due in the early part of the year or in colder climate,
birth later than average, and that those mares due in the early
spring or in warmer climates are more likely to birth on time or a
bit earlier than average. Could this be because the foals born in
colder climates and earlier in the year need to grow a longer coat
of fuzz before they pop out?
Foal heat is normally 10 days post
foaling. Again there is a lot of variance. Our favorite mare comes
in 18 days post foaling.
Use these calculators
to check your Mares Foaling Date:
Equine Foaling Estimator