By the time a broodmare enters her late teens and early 20s, her reproductive ability begins to decline, and getting and keeping her pregnant become more problematic. The causes of reproductive difficulties in the older mare are numerous, but in many situations, good management, accurate diagnostics, and appropriate medical or surgical therapies can optimize the chances of producing healthy foals right up until the time there are essentially no more eggs in the basket.

Pregnancy Prohibitors

Contamination and infection, both of which can cause an inflammatory response, are primary reasons for reproductive failure in the older mare. The presence of inflammation in the uterus can destroy the semen or embryo.

In the aging mare, the leading cause for contamination and infection is poor anatomical conformation and, consequently, the reduced efficiency of the anatomical barriers that help keep infection and urinary, fecal, and air-born contaminants out of the reproductive tract. John Dascanio, VMD, Dipl. ACT, Dipl. ABVP, Associate Professor, Equine Field Service/Theriogenology, Virginia-Maryland Regional College of Veterinary Medicine, identifies the three most common conformational disorders. The first barrier to infection is the vulva. A number of older mares ‘will have a tilted vulva where their anus is sunken inward,’ he says. ‘This causes the vulva to tilt, allowing the mare to defecate on top of her vulva and contaminate her reproductive tract. In addition, the lips of the vulva may not seal as tightly, often due to multiple Caslick’s operations or past trauma.’

The second barrier is the vestibu