What is the “Normal” time before delivery for a maiden mare to “bag up”?

I have a 13 year-old maiden mare that should be due the first week of May (for the 338-342 day mark). At this point she is showing very little udder development. She does have a large abdomen (and was confirmed in foal in Nov). I do not believe she has been ...I have a 13 year-old maiden mare that should be due the first week of May (for the 338-342 day mark). At this point she is showing very little udder development. She does have a large abdomen (and was confirmed in foal in Nov). I do not believe she has been ...

Story originally posted by: Michael Lowder, DVM, MS

Dr. Lowder:

I have a 13 year-old maiden mare that should be due the first week of May (for the 338-342 day mark). At this point she is showing very little udder development. She does have a large abdomen (and was confirmed in foal in Nov). I do not believe she has been grazing on fescue and she was brought into a stall the first of April. Is this a serious cause for concern? I have heard that older mares will frequently carry longer. What else should be watched for?

Thank you.

Dear Kathy,
Older mares may have a slightly longer gestation as you guessed. Prolonged gestation (greater than 365 days to 480 days) has resulted in delivery of healthy foals. During late gestation, there is often a "sinking" on either side of the tail head due to relaxation of the ligaments (in older mares, this may not be as obvious).

During last few weeks, the vulva will become swollen and begin to lengthen. The most reliable indicator of impending birth is the development of the mammary glands (although maiden mares can prove to be the exception to the rule!) and this begins about 4-6 weeks before birth with the greatest growth the last two weeks.

During the last 2-3 days, you may see colostrum oozing from the teats with a wax-like coating on the tip. It is reasonable to expect foaling within 24-48 hours after waxing. Good luck and happy foaling!

Dr. Lowder