FAQ Is My Mare Too Old by Jamie Anderson

One of the most-asked questions by new and amateur breeders is: “Is my mare too old to have a foal?” In most cases, there isn’t a ‘Yes’ or ‘No’ answer to this question. Generally, when a mare is too old, you will simply not be able to get her in foal. Although there is no such thing as an equine menopause, a mare’s reproductive system will often shut down when she is no longer capable of carrying a healthy foal to term. However, this is not always the case and sometimes you will have to make the decision as to whether or not you should try to put your older mare in foal.

There are no hard and fast rules in equine reproduction. However, in general if a mare is older than 12, then she is considered to be an “older” mare, and will need to be treated as such – with a combination of pre and post breeding treatments, and possibly a special insemination regime. Older maiden mares can be even more difficult, and may need further treatments and intervention in order to become pregnant.

The table below is a rough guide to whether or not a mare is too old to be put in foal, and what problems and treatments must be used with mares of different age groups.

This table is not comprehensive, and your mare may not fit the descriptions, but many will. The age-related problems and required treatments are not exhaustive, but should give you some idea of why older mares can be more difficult to get in foal, and the extent of the additional treatment that may be required for them to become pregnant. It should be noted that the chances of successfully getting a mare pregnant fall quickly through her teenage years, and by the age of 18+ a significant number of mares will have a 10-15% chance of conceiving and carrying a healthy foal to term.

If you are considering putting an older mare in foal, then you should get her fully checked out by a specialist reproductive/stud vet at the start of the season. This should include a uterine culture, cytology and biopsy. Use a reputable AI centre or stud, experienced in dealing with older mares, where the staff are able to discuss the possible problems associated with older mares with you. Some studs and AI centres offer an “older” or “problem” mare AI package which is a good sign that they are aware of the potential problems involved with trying to get older mares pregnant.