Good question. While 370 days is well within an acceptable range, there are multiple issues to consider when determining whether to worry or not.
1) Is/are the actual breeding date(s) known? Realize that the mare could ovulate 2-3 days after she was last bred. If pasture bred she may have cycled back in without being observed and the gestational age of the foal could be 20 or more days different than the breeder realizes.
2) The mare could be carrying twins. Because twins get only half of the nutrition normally given to a single foal maturation is slower. Most breeders will insure that
twin pregnancies are eliminated early in the breeding process (at 14-16 days post ovulation) because successful foaling of two live twins is actually quite rare and because the possible complications (abortion, dystocia, etc.) result in both economic and emotional loss due to veterinary costs or death/injury of/to the mare or foal(s).
Generally, mares that produce twins (succesfully or not) are also more likely to lose the subsequent breeding season.
3) If the mare is older her foal may require additional time to mature because of wear and tear on the uterus.
4) Breeding dates were inaccurately recorded or mixed up with another mare.
5) If the mare was poorly nourished or ill at some point during the pregnancy foaling
can be delayed.
These are the most likely causes of prolonged gestation that are not, in and of themselves, a cause for worry.
Other possible causes that are more concerning.
1) Fescue toxicosis
2) Exposure to spoiled/moldy corn based products. This results in a prolonged gestational period and large, limp (dysmature) foals.
3) Wry foal, body pregnancy, hydroallantois (often these foals are premature but not always).
4) Other (rarer yet) issues. (That's helpful isn't it?)
Finally, since the question about whether or not to worry (you are already worried, right?) is being asked, the mare owner needs think about their level of experience and determine if the best course of action is to get an opinion on the status of the mare and her foal from a veterinarian or more experienced horseperson. There is a lot of time, energy and emotion already expended while waiting for this mare to foal
a little money spent now to be reassured (or forewarned) is probably well worth it.
A mare is pregnant for around 11 months, which is roughly 44 weeks. The gestation period for a horse is typically between 320-370 days.
The same length of time as other full sized horse and pony breeds, around 11 months.
A mare is usually pregnant for just shy of a year, but it depends on the horse though.
A female horse, or mare, is pregnant for about 11 months before giving birth to a foal. The gestation period can vary slightly, but typically ranges from 320 to 370 days.
"Gestation" means length of pregnancy, or rather how long a female horse, being a mare, carries a foal, from conception (mating with stallion) to birth. Gestation for a horse is typically 310 days, which is generally considered the lowest number of days to produce a viable foal, without special care/veterinary treatment. However a mare can be pregnant up to 370 days...with 340-345 days the norm.
1 year = 365 days 365 days + 5 days = 370 days 370 days x 24h/day = 8880 hours
Mares are usually pregnant 320 - 360 days. A foal can become post-mature before reaching the 360 day mark. When a foal is post-mature, he begins to weaken as the placenta cannot support him properly.
The average is about 340 days, but a healthy gestation period can be as short as about 310 or as long as about 370
8,880
Around 11- 12 months. If a mare is pregnant for the first time, then she may carry her foal longer. They can also carry the foal slightly longer if it is a colt versus a filly.
15 days and 10 hours.
Days of Our Lives - 1965 1-370 was released on: USA: 19 April 1967