Dr. Elaine Carnevale

It’s early morning in the “Princess” Barn and the residents are waking up, softly whinnying to each other while waiting for breakfast to be served. These ladies in waiting are treated like royalty and Dr. Elaine Carnevale makes no apologies for that. The mares are her charges and she wants to make sure they get only the very best.

The mares are at the Equine Reproduction Laboratory for reproductive assistance, whether to increase reproductive success in older or problem mares, or to obtain a pregnancy from a stallion with limited or poor quality sperm. Whatever the problem, Dr. Carnevale, an Associate Professor in the Department of Biomedical Sciences, helps to find a solution to safeguard the mare’s lineage and ensure her valuable genetic material will be conserved.

“Fertility starts to decline in mares in their teen years, when we see similar hormonal changes to what women begin to experience during perimenopause,” said Dr. Carnevale, who is a member of the research team at the Equine Reproduction Laboratory. “Many of our assisted reproduction techniques help prolong the reproductive life of the mare by using such technologies as oocyte transfer, embryo transfer, sperm injection or other technologies. We also are working to understand how aging affects reproduction. It’s all about optimization.”

When Dr. Carnevale came to Colorado State University in 1998 she began a clinical oocyte (egg) transfer program to obtain pregnancies from mares that were no longer able to get pregnant or provide embryos. This evolved to include the collection of oocytes from the ovaries of mares after they had died. Work done lately includes sperm injections (an assisted test-tube fertilization to obtain foals from subfertile stallions) where sperm is injected into the eggs from young and older mares to improve conception rates.

Grad students palpating mares

Dr. Carnevale’s clinical program is based on referrals so horses of all breeds come from across the United States (and some from other parts of the world) for treatment. The mares usually stay about six months out of the year, with the clinical team working to ensure the highest level of care and the best possible reproductive outcome. Dr. Carnevale works with mares of all ages, often as old as 25. The reason being, she notes, is that mares are limited in the number of foals they can produce, and their value may take a number of years to establish.

“The mare may be older by the time her value as a broodmare is recognized,” said Dr. Carnevale. “We work with a lot of very good older mares with compromised reproduction. A lot of horses also will continue to perform in reining, racing, cutting, dressage and jumping, limiting their availability for pregnancy. In all cases, their owners want to preserve the mare’s line and produce more foals. Our goal is a healthy pregnancy and a healthy baby.”

In her research program, Dr. Carnevale and her team continue to improve the science behind using sperm injections to artificially fertilize eggs. In another research project they are studying the egg and its interactions with the follicle. This would include the signals between the egg and follicle that result in egg maturation (preparation for fertilizations) and ovulation. An important component of the work is how these signals differ in old and young mares.

“One interesting aspect of our work with older mares is how it relates to fertility in humans,” said Dr. Carnevale. “A lot of the same things that happen in the horse happen in the woman, including a long follicular phase, one ovulation, and a similar length of time for the egg to mature before ovulation. Some of the reproductive problems we see are also very similar, as more women wait until they are older to have children. Mares will probably make an excellent model for human reproductive studies and the information we gain can be used to benefit both species.”

The Equine Reproduction Laboratory is offering two short courses for veterinarians this fall focusing on reproduction and the mare. On Sept. 26 and 27 is the Equine Reproduction Symposium – The Problem Mare. On Sept. 24-25 is the Equine Embryo Transfer Short Course. These are hands-on courses with limited enrollment. For additional information visit the Equine Reproduction Laboratory Short Course website.