Successful Breeding of Older Maiden Mares

Success when breeding older maiden mares depends on the management of several factors that contribute to the retention of excessive fluid in the uterus, including insufficient lymph drainage, a uterus hanging over the pelvic brim, and a tight cervix, according to Jonathan Pycock, B. Vet. Med, PhD, DESM, MRCVS, of Equine Reproductive Services, North Yorkshire, England. Pycock explained his approach at the AAEP Convention 2006.

"Unless your therapy program addresses all these problems, it's going to end up not doing quite the job it ought to do," Pycock said. "If you're going to come across one of these very susceptible maiden mares, it's important to pull all the stops out the first time you inseminate her."

Semen causes an inflammatory reaction in the uterus, prompting the production of fluid to clear the uterus of the semen. However, in some mares, this fluid does not clear the uterus. The resulting inflammation decreases the chances of embryo survival. According to Pycock, it's normal to see fluid in the uterus up to 12 hours following breeding, but some mares retain fluid beyond 24 hours. These mares require some special management in planning the breeding process, during breeding, and after breeding to have the best chance of pregnancy success.

To manage these mares, Pycock recommended practitioners understand how the uterus reacts to breeding and how therapeutic options will address this reaction, then formulate the best approach for their practices.

Pycock suggested that care be taken when scheduling the breeding of these mares. Using ovulation induction agents can help practitioners to more accurately estimate when the mare will ovulate. Timing is important, as endometrial edema scores (amount of fluid in the uterus) decrease 24 to 36 hours before ovulation. It is ideal to breed these mares between one and three days before ovulation as long as they are naturally covered or inseminated with fresh semen. If permitted by the breed registration, fresh semen insemination is preferable to natural covering to reduce the challenge to the uterus.

Scanning the mare for fluid often prior to breeding can help practitioners know if fluid is present, in which case Pycock suggests using oxytocin to clear the uterus for breeding. According to Pycock, it is easier to breed older maiden mares on their second ovulation of the year, as the ovulation date is easier to estimate.

When breeding the older maiden mare, Pycock said good hygiene and opting for artificial insemination can help decrease the amount of bacteria in the uterus.

"Post breeding, you've got to come up with a treatment protocol for situation and type of mare you're dealing with," Pycock said.

This treatment can include the administration of oxytocin every six hours post-breeding, or every four hours in certain cases, alternating between short- and long-acting formulas. Pycock also suggested uterine flushing, broad-spectrum antibiotics, and dilating the cervix.



Get research and health news from the American Association of Equine Practitioners 2006 Convention in The Horse's AAEP 2006 Wrap-Up sponsored by OCD Equine. Files are available as free PDF downloads.

About the Author

Erin Ryder

Erin Ryder is a former news editor of The Horse: Your Guide To Equine Health Care.

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