Mares are often very unpredictable in showing signs of foaling. The gestation length can vary several weeks and many evening and nights can be wasted sitting up watching and waiting for the foal to arrive. It is generally agreed that the average length of time that a mare is pregnant is approximately 335-340 days; however, normal ranges between 320 – 360 days are often quoted by experts in the field of broodmare management.
These can vary considerably from mare to mare. Maidens may show no signs whatsoever before they foal, while other mares may show every conceivable sign for 3 to 4 days or even longer. The indications given below should only serve as a general guideline.
(a) Distention of the udder - this can occur for up to 6 weeks prior to delivery of the foal, but usually begins to appear 2 – 4 weeks beforehand and increases gradually as parturition becomes more imminent.
(b) Slackening of the area around the buttocks and the base of the tail - this is something that is only detectable by frequent examination of the area. The slackening usually starts 1 – 3 weeks before the foal is born, and by the time parturition occurs the region around the base of the tail is very loose feeling.
(c) Filling of the teats - usually starts to occur a week to ten days before the foal is born.
(d) Wax on the teats – this occurs in approximately 60% of mares and is one of the more reliable indicators of impending parturition. Most mares will foal within 2 – 3 days of the wax appearing.
(e) Loose vulval lips – this may be often difficult for the inexperienced person to judge, but the best way may be to compare with another mare in the area. Excessive slackness of the vulval lips usually indicates parturition within 48 hours.
(f) Milk dripping from the udder – is a sign that foaling is very imminent i.e. within 12 – 24 hours. Some mares however will “run” their milk for several days and these mares will often have an internal problem, such as an infected placenta. Valuable colostrum is also lost during the process, and it is advisable to consult your veterinarian if this is occurring.
We recommend that you start testing your mare approximately 10 days before she is due, based on an average gestation length of 340 days. The Gestation Table in the PAF kit will help you to determine this date. If you do not have an accurate breeding date you should attempt an initial test as soon as the udder begins to enlarge and secretion can be obtained from it. Some mares will begin mammary development much earlier than expected. This can be due to various factors including the presence of twins, an impending abortion or a wrong breeding date. Mares foaling between 300 – 320 days will produce premature foals and particular attention will be needed to ensure every possible chance of survival of the foal.