Texas A&M Theriogenologist Explores Alternate Method of Identifying Genetic Disease in Horses

Horse and her foalDr. Allyson Ripley, a senior equine theriogenology resident in the Texas A&M College of Veterinary Medicine & Biomedical Sciences (CVM), has been working on an exciting research project for the last year that aims to find an alternate means of determining fetal genotype.

Currently, determining if future offspring will be filly or colt, roan or sorrel, or a carrier of one of the many genetic diseases seen in the Quarter Horse breed, such as HYPP, can only be done by waiting until the foal is born or by performing embryo biopsy in the very early stages of pregnancy.

“Embryo biopsy has many costs and considerations involved with its completion and, therefore, may not be an option for everyone,” Ripley said. “Is there another clinically feasible way that private practitioners could obtain the DNA needed for these tests early in pregnancy without the costs and efforts of embryo flushing, sampling, and transfer? That is exactly what this study was designed to explore.”

Funded by the Legends Premier Stallion Season Auction, the research took ideas from human medicine’s amniocentesis procedure performed on pregnant mothers and expanded them with techniques already used in other equine reproductive procedures.

“In the case of identifying carriers of genetic diseases, it would be ideal to receive DNA results and make decisions in a timely manner early in pregnancy so as to be able to rebreed in the same season, if necessary,” Ripley said.

The procedure developed in this study allowed for fetal DNA samples to be obtained and successfully analyzed from pregnancies that were less than 30 days of gestation.

“Due to the nature of developing new procedures and the invasiveness of acquiring DNA from a fetus residing inside of the mare, there were some potential risks to the developing pregnancy,” Ripley said. “Because of this, three of the pregnancies were allowed to develop to term, both to monitor the remaining 10 months of gestation and to assess the resulting foals.”

Researchers were excited to find that all three pregnancies resulted in normal, healthy foals that were born in April.

Although this procedure is not yet ready for clinical application, its development and current success has sparked the possibility for new a method of genetic analysis in the equine industry.

“Projects like this and others performed at Texas A&M University, with support from the Legends Premier Stallion Season Auction, are what keeps this industry advancing, and that is made possible by the generous contributions of our donors,” said Warren W. Hohertz, program coordinator for Equine Reproductive Studies/Legends Premier Stallion Auction. “We thank you immensely for your unwavering support!”