Mares with sex reversal syndrome usually look normal (like the mare on the left), but are infertile and can exhibit some masculine behaviors such as trying to mount another mare. | Photo: Courtesy Dr. Sebastián E. Demyda-Peyrás

“We now have the possibility to detect more than 90% of the chromosomal abnormalities in horses based on a simple blood and hair DNA sample, with a confidence level higher than 99%,” said Sebastián E. Demyda-Peyrás, MSc, PhD, of the University of La Plata Institute of Animal Genetics, in Argentina.

The research team based their test on the detection of seven single-tandem-repeat (STR) markers they identified in 2015, Demyda-Peyrás said. Five of the markers are located on the X chromosome and two on the Y chromosome.

They validated their new test in a population of 271 male and female purebred Spanish horses. Ten of the horses had already been diagnosed with sex chromosome disorders through the more complicated and expensive karyotyping test. Two of the 10 were chimeric, two had Turner’s syndrome, and six had sex reversal syndrome