Ask A Geneticist: Why Do Icelandic Horses Have More Gaits Than Most Horse Breeds?

In addition to most horses’ usual three gaits, the Icelandic horse is well known for having two more: tölt and flying pace. We wanted to know what lies behind the Icelandic horse’s two unique gaits, and asked geneticist Dr. Freyja Imsland.

The ancestor of the horse had three ways to move: they could walk, trot, and gallop. Sometime after people began domesticating horses, a horse was born that could move differently. Our ancestors noticed this, and made sure to get offspring from that horse. These horses were much softer to ride than other horses.

When the settlers brought horses to Iceland, they brought their best horses—horses that had what we call the noble gaits, “tölt” and “pace.” Tölt is a four-beat gait that’s very comfortable to ride, even for new riders. Pace is a two beat gait, where the legs on the same side of the body move together, and horses can go very fast. In Iceland, most people ride their horses across the country in tölt, and we have flying pace races for the fastest pacers. This summer Kjarkur frá Árbæjarháleigu II set a world record at the Landsmót event for covering 250m in 21.15 seconds.

The reason the Icelandic horse can tölt and pace is that there was a DMRT3 gene mutation. This gene is responsible for synchronising the left and right sides of the horse’s body, and this change means that the legs can move in new patterns, and also that the horse can run faster without breaking into gallop. This means that it is not only soft-gaited horses like the Icelandic horse that have this ability—harness-racing horses that race in trot do too, because they can trot faster than horses without the gene change.

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