Early this year, frozen embryos that had undergone genetic testing were thawed and successfully transferred into the uteri of surrogate mares at Minitube International Center for Biotechnology, in Mount Horeb, Wis.

The benefit of genetic testing of embryos is the ability to detect genetic diseases and traits prior to establishing a pregnancy. There are numerous diseases for which genetics have been identified, including muscle disorders in Quarter Horses, neurologic disorders in Arabians, and a lethal gene associated with particular coat color in Paints.

Mats Troedsson, DVM, PhD, Dipl. ACT, director of the University of Kentucky’s Gluck Equine Research Center and chair of the Department of Veterinary Science, was the principal investigator for the research project. Troedsson is also a consultant for Minitube.

Researchers collected six 1/2-day-old embryos from eight mares and obtained biopsies from embryos. They cryopreserved (preserving tissue under freezing conditions) the embryos immediately after obtaining the biopsies. They used PCR (polymerase chain reaction), a common laboratory tool to identify genetic material in a sample, to determine gender on the biopsied cells. Gender determination was used as a model for genetic testing in this study. The cryopreserved embryos were then thawed and transferred into the uterus of surrogate mares. Six out of the eight embryos developed as pregnancies