It is very normal for mares to carry a fetus for 320 to 380 days. In general 330 days (11 months) is the most commonly cited gestation length.
The average gestation length (pregnancy) is 11 months and a week – 335 to 342 days. However not all mares read the text book and foals can be born from 320 days to 365 days (and beyond!) without any adverse effects to the foal’s health.
Signs of pregnancy can be detected by a Veterinarian through a rectal examination. This can be done within three weeks of the mare’s covering and the vet will place his hand in the rectum to palpate the uterus and assess its size, shape and also any swelling of the ovaries.
Mares have been known to go a full 12 months and beyond, causing serious consternation for owners and attendants. Generally, a mare will follow a pattern as to gestation length. For this reason, it is wise to keep complete records throughout the pregnancy, including previous foaling dates.
Mares generally foal at night. One study, for example, indicated that approximately 80 percent of foals were born between midnight and 6 a.m.
A pregnant mare’s stomach will appear slightly bloated even though she is up to date on worming. A mare who is nearing her delivery will often appear to have a larger-than-average belly. In comparison to the belly, the rest of the mare’s body should appear proportional and in good weight without excess fat.
Although wax and milk secretion usually indicate delivery will occur very soon, many mares foal without either, while some mares drip or stream milk for several days before foaling.
If disturbed, the mare may delay foaling, or worse, may do serious damage to herself or to her foal. Under natural conditions mares most commonly foal in late spring when temperatures are most likely moderate and optimal feed will be available for the post-natal period.
The placenta is expelled after the foal has hit the ground and we collect it. The mare licks any remains of the placenta away from the foal’s nose and mouth if necessary so that he can breathe and begin to suckle. Later she licks the rest of the residual bits off, but she doesn’t consume it, just licks it.
Yes, pregnant mares will let a stallion breed. It’s best to have a vet find out for you so you can breed her of she’s not, or separate them if she is.
Human pregnancy tests -do not- work in equines. Human pregnancy tests tend to measure levels of Human Chorionic Gonadotrophin (hCG). Equines do not produce hCG. They produce Equine Chorionic Gonadotrophin (eCG, previously known as PMSG – Pregnant Mare Serum Gonadotrophin).
It’s not a good idea. The American College of Obstetricians and Gynecologists recommends avoiding activities that entail a high risk of falling or abdominal trauma.
Physical signs of impending parturition include vulvar laxity and edema (swelling), and small amounts of clear (mucus) discharge. … The mare’s udder will enlarge and begin to produce a “waxy” yellow secretion (colostrum) as near as one to two days before foaling, but sometimes as long as two weeks prior to parturition.