Pre-implantation genetic diagnosis (PGD) is a procedure used to screen embryos recovered after uterine flush to determine sex and genetic traits through DNA testing prior to implantation in the uterus. DNA testing of horse embryos prior to implantation allows selection of those embryos that have desired sex, coat color variants, or that are free of known genetic diseases, thus maximizing the outcome of embryo transfer process.
The Veterinary Genetics Laboratory offers DNA tests on horse embryo biopsies for sex, genetic disease (GBED, HERDA, HYPP, Lethal White Overo, Malignant Hypothermia for Quarter Horses and related breeds, or CA for Arabians) and coat color (Red Factor, Agouti, Champagne, Cream, Dun, Pearl, Silver, Lethal White Overo, Gray, Sabino-1, Tobiano, Dominant White W10, Splashed White).
Biopsies are performed on Day-6 or Day-7 blastocysts from which 5-10 trophoblast cells are harvested by suction. Cells are placed at the bottom of a 0.2 ml, thin walled tube in 1-2 microliters of PBS, 2% PVP buffer, or other cell culture medium and frozen. The volume of medium is critical. Liquid in excess of 2 microliters negatively affects the process of whole genome amplification and may result in test failure. Tubes are shipped overnight on ice or dry ice via DHL, FedEx, or UPS. Embryo biopsies are received Monday-Wednesday, with results available within 36 hours.