Embryo transfer has been well-established in the horse industry as a method of obtaining multiple offspring from a valuable donor mare. The increased usage of this technique prompted Colorado State University (CSU) researchers to examine the effects of repeated embryo flushing. Elaine Carnevale, DVM, PhD, from CSU’s Animal Reproduction and Biotechnology Laboratory, presented the study’s findings at the 51st Annual American Association of Equine Practitioners Convention, in Seattle, Wash., Dec. 3-7, 2005.

“The advantages to obtain more than one foal during the breeding season is obvious for the owner, but what we are doing to the mare by multiple embryo transfers is insulting the mare’s uterus,” Carnevale explained.

In the study, funded by the American Quarter Horse Association, the researchers found that repeated inseminations and embryo collections were associated with increased chronic uterine inflammation, but were not associated with increased infectious organisms within the uterus.

“During insemination, a significant insult occurs in the uterus,” Carnevale reported. “If contamination is not overwhelming, the healthy uterus contends with the invasion through a series of events, resulting in an inflammatory reaction that helps to clear the uterus of sperm and contaminating debris