For those with mares and interest in using a marble... this question was
posed in the AAEP weekly newsletter, It's pretty interesting.
Last issue we asked:
I have a mare that is typically difficult to train this time of year due to
"exaggerated" spring estrus symptoms. My vet has suggested, as an
alternative to Regumate, the insertion of a sterilized marble into my mares
uterus. I am concerned about risking her future fertility, as I may want to
breed her in a few years. What are your thoughts on this procedure regarding
efficacy and long-term fertility?
The answer is:
This technique was described at the national AAEP (equine practitioner)
meeting about two years ago. You induce heat or wait on a heat cycle. When
the cervix opens, then you induce ovulation. After you prep the mares
vulva, you then insert a sterile marble. This simulates a conceptus for the
mare. The marble is non-irritating, if done correctly, is sterile, and far
safer for the future of the mare than progesterone implants (used in feedlot
cattle). Besides the fact that Regumate is messy, expensive, has to be given
every day, and is not a good idea for a human female to handle since it
absorbs through the skin. As a side note, it is a very common practice to
breed racing mares, get them pregnant and continue to train them for racing
for 3-5 months after they conceive...but in answer to your question, the
marble idea was adequately researched and a common practice in many
reproductive practices. Benjamin Espy, DVM, Lexington, KY