Racehorse Lead Preferences Studied

Horses moving at a gallop display one of two four-beat footfall patterns, right lead or left lead, depending on which hind foot begins the pattern. Horses on the right lead show a footfall pattern of left hind, right hind, left fore, right fore, followed by a period of suspension when no hooves touch the ground. Horses on the left lead show a footfall pattern of right hind, left hind, right fore, left fore, followed by a period of suspension when no hooves touch the ground. This transverse gallop seems to be used by horses to avoid interference (hitting one leg or hoof with another).

A somewhat similar four-beat gait known as the rotary gallop has an identical first and second footfall, followed by a reversed order of the forefeet. For example, the animal’s footfalls might be right hind, left hind, left fore, and right fore. This is the preferred gait of some animals including the cheetah, which has a more flexible spine and more lateral swing to the legs. The rotary gallop is a rough, awkward gait for horses to sustain, and few horses stay in this footfall pattern for more than a few strides.

When horses negotiate a turn, they usually choose to gallop with the leading leg corresponding to the direction of the turn; hence, a racehorse turning to the left is most balanced and comfortable on the left lead. On a straight course, either lead can be used, and horses tend to change leads several times during a race. The author suggests that the choice of lead may be linked to biomechanical factors affecting ease of breathing (each complete gallop stride is accompanied by one inhalation and exhalation) or “handedness” (individual preference for one lead over the other).

This locomotion study was designed to determine if individual racehorses have a preferred lead at the gallop, and to compare the characteristics of right-lead and left-lead gallop strides for the same horse.

How was the study conducted?

Live observations were conducted of male and female Arabian, Quarter Horse, and Thoroughbred racehorses as the horses made the trot-to-gallop transition during warm-ups and training sessions. Trot-to-gallop transitions were observed in 209 horses. Arabian and Thoroughbred horses are often raced around turns, and therefore may be taught to pick up a specific lead, while the observed Quarter Horses were raced only in a straight line and presumably were not influenced as to a particular lead.

Race videotapes were used to determine the leads of horses breaking into a gallop from the starting gate at the beginning of a race (n=9,116). Videotapes were used to determine the leads of another 32 horses, each starting in 5 to 7 actual races, at San Luis Rey Downs.

To compare stride patterns used in right- or left-lead gallop, five Thoroughbreds were used. All horses had the same trainer, training schedule, and rider. In addition, all were similarly shod, had the same feeding program, were given free-choice water, and were stabled in the same barn in individual stalls.

Each horse was asked to run a series of sprints of various distances. The horse was warmed up and then eased into a gallop before passing a pole designating the start of a measured distance. Each horse ran alone, was kept on the rail during the trial, and went around a turn and through a straight stretch. The track was harrowed before each trial. Observers noted when horses changed leads after the turn, and marked tracks from the two strides before (strides 1 and 2 of the series) and two strides after (strides 3 and 4) the lead change. Assuming that the strides immediately before and after the lead change (2 and 3) might have been atypical because of the mechanics of the change, researchers recorded patterns of the strides just outside this window (strides 1 and 4). They measured the orientation of each footfall, plotted the four footfalls as a pattern, and superimposed the mirror image of stride 4 onto the pattern of stride 1 to ascertain the degree of similarity.

What results were found?

Among all horses in the Thoroughbred, Arabian, and Quarter Horse groups, numbers were quite similar for lead preference when breaking from a trot to a gallop. A range of 91% to 92% of horses preferred the right lead in this situation, while the remaining 8% to 9% preferred the left lead. Numbers were very similar for male and female horses, and these numbers held steady when the horses were observed on different days and when working on different sections of the training track.

Lead preference was recorded for horses breaking into a gallop from a standstill in the starting gate.

A total of 6,313 horses were observed in 9,116 starts. Although the right lead was still far more popular in all groups, there was a slight variation by breed. Among Thoroughbreds, 91% preferred the right lead and 9% preferred the left lead. Among Arabians, 88% preferred the right lead and 12% preferred the left lead. Among Quarter Horses, 89% preferred the right lead and 11% preferred the left lead. The author mentioned that, on occasions when he observed ten female Thoroughbred horses racing in Dubai, nine broke from the starting gate on the right lead and one broke on the left lead. On replays of several Australian races in which the horses ran clockwise, 89% of horses were on the right lead and 11% were on the left lead.

As to uniformity of footfall pattern in right and left leads, no tested horse showed an exact matching mirror image of footfalls. Differences were seen in lateral placement as well as length of stride, with stride length being slightly greater for horses on the left lead in four out of a group of five horses.

What does this study tell us about lead preference, and are there implications for effects on gait efficiency?

The author mentions several areas for thought or further study:

• Preference for a particular lead may or may not have a parallel in human “handedness” and may or may not be due to brain hemisphere dominance. Such correlations can’t be inferred or ruled out by this study.
• The fact that galloping horses take one breath per stride is related to gait mechanics. Because stride length and pattern are imperfectly matched on the left and right lead, it is possible that breathing is more difficult and/or less efficient while the horse is on the non-preferred lead. If so, this could have an effect on speed, endurance, and fatigue.
• A number of factors (conscious or unconscious cues from rider or starting gate worker, for example) may affect choice of lead. Also, footfall pattern and length of stride may change throughout the course of the gallop according to fatigue, rider cues, track surface, or other factors.
• More research may shed light on lead preference and its effect, if any, on gait efficiency.

This summary is based on an unpublished Masters thesis (2002).

The study, “Stride pattern preference in racehorses,” was conducted by DE Williams, California State University-San Marco.