"You think breeding mares on foal heat is tough, try dead mares!" said Elaine Carnevale, DVM, PhD, professor in equine reproduction in the department of biomedical sciences at Colorado State University (CSU), with a laugh as she began her talk following a presentation on foal heat breeding success. Her presentation at the 50th annual American Association of Equine Practitioners (AAEP) Convention in Denver, Colo., Dec. 4-8, 2004, covered CSU's work with deceased mares' ovaries and oocytes, and their success rates.

"Death or euthanasia of a valuable mare results in loss of her genetic potential," she said. "However, when a mare dies, her ovaries still contain potentially viable oocytes that can be harvested to produce additional offspring. Some mares seem to have a lot of viable oocytes, while others have very few."

Factors that can affect this are:

• Donor variability;

• Age and fertility;

• Time of year (seasonal variations in ovarian activity);

• Quality of oocytes;

• Medical history and treatment;

• The interval from death to harvest and use; and

• The transportation interval and conditions.

"This technique also has clinical use," Carnevale added. "In 2001, a Quarter Horse mare was euthanized, and her ovaries were transported to CSU. We transferred five oocytes, had five embryonic vesicles in a recipient's uterus, and got a healthy foal