The average gestation length for mares is 340 days although
this can vary widely and can be as long as 360 days or more.
Factors that may affect the length of gestation include sex of the foal,
season, maternal nutrition, ingested toxins and environmental stresses.
the last month of gestation, the mare should start to be checked for physical
changes that indicate nearness of delivery.
These changes include development of vulvar laxity, relaxation of the
pelvic ligaments, udder enlargement, and a change in the amount and character of
Mammary gland growth becomes apparent most dramatically
within the final 2 weeks of gestation. The
accumulation of waxy secretion on teat ends from early colostrum formation
usually occurs 1-4 days prior to foaling, although many of these parameters vary
widely between mares as well as within individual mares depending on how many
foals she has had previously. Some
multiparous mares may even leak milk within the last couple of weeks of
gestation, leading to a depletion of colostrum.
Often, secretions immediately prior to foaling have a thick, sticky
consistency and can be more yellow than white in color.