Common to all horses are four basic gaits: walk, trot, canter, and gallop. Gaited horses throughout the world, however, possess the ability to perform certain alternate forms of movement relative to their breed. A team of Swedish researchers discovered that genetic makeup affects locomotion patterns in horses, allowing for gaitedness through two separate effects: extra gait in some breeds and fast trot in harness racing horses.

Studying Icelandic horses using genome-wide association analysis and whole genome resequencing, the team determined that a genetic mutation facilitates the lateral gaits ambling and pacing. “We managed to identify a novel gene, DMRT3, which regulates the pattern of locomotion,” explained Lisa Andersson, PhD, of the Swedish University of Agricultural Sciences, in Uppsala. “DMRT3 is specifically expressed in the spinal cord; we propose that the mutant variant somehow makes the spinal cord more flexible.”

The team concluded that homozygosity (possessing two identical forms of this gene, with one inherited from each parent) for the DMRT3 mutation is necessary for pacing. “Only Icelandic horses with two copies of the mutant gene variant can perform the two-beat lateral gait, flying pace,” explains Andersson.

The team noted this mutation is conducive to other gaits, such as ambling and pacing, in other gaited breeds besides the Icelandic. The mutation is also favorable for horses used in harness racing, as it allows them to trot at a higher speed before breaking into canter