Laterally Coordinated Gaits in the Modern Horse (Equus ferus caballus)

Abstract

Besides “natural” gaits of walk, trot, and canter, selected horse breeds engage in the so-called artificial gaits, including the fox trot, running walk, and rack. Though some studies have been undertaken of these artificial gaits, the datasets are incomplete, sample sizes are small, and no comprehensive overview has been written. After reviewing the literature and detailing what is known about these artificial horse gaits, the authors present data of their own. Linear, temporal, and footprint parameters or given regarding artificial gaits of twenty horses total from specialized breeds. In addition to finding decreasing stride duration, lateral advanced placement, and tripedal support as one moves from the walk to the running walk to the rack, as with previous studies, we also found decreasing ipsilateral/diagonal step time ratios and increasing ipsilateral swing phase overlaps. Visually, the walk, trot, fox trot, and slow rack leave trackways of ipsilateral pairs in parallel rows, the running walk and canter leave trackways of isolated prints with the running walk pattern more symmetrical, and the fast rack, stepping pace, and pace leave trackways with an undulating pattern formed by diagonal pairs of hooves with hooves often crossing over the center line yielding a negative interior straddle.

New Studies on the Gaits Displayed by Miocene, Pliocene, and Pleistocene Fossil Horse Trackways

“…Key linear parameters and ratios were recorded from the data, sketches, and descriptions of the fossil horse trackways, as were the footprint patterns found therein. Based upon our previous work on modern horse gaits [7,[23][24][25]34], and further refined here, the key linear kinematic parameters, ratios, and footprint patterns useful for the determination of horse gaits are as follows (definitions modified from [35]; see Figure 1).…”

“…This is why trackway data is important, especially the size of the front hoof print. Still correlation of hoof size with horse height is lower (0.41) than that of a correlation of other skeletal elements such as the skull (0.83-91), metacarpal (0.90-0.95), metatarsal (0.87-0.91), and phalanges (0.81-0.91) (see [34,[36][37][38][39][40]). Moreover, the allometric ratios of the different limb bones can vary from one species to another [41][42][43] and this can affect height estimations.…”

“…Based upon dimensionless speed, gaits are separated into slow walks (SL/HT = 0.78-1.09) and fast walks (SL/HT = 1.10-1.18); slow trots (SL/HT = 1.32 = 1.51) and fast trots (SL/ HT = 1.55-1.80); slow running walks (SL/HT = 1.13-1.36) and fast running walks (SL/ HT = 1.59-1.60); slow racks (SL/HT = 1.18-1.24) and fast racks (SL/HT = 1.39-1.70). Key linear measurements and ratios of modern horse trackways in different gaits (data from [25,34]; and original data, 2022).…”

“…This is based upon the fact that they are set down in a pattern of capping or slightly overstepping ipsilateral prints (ipsilateral step distance/stride length ranging from À0.05 to À0.08), at a moderate speed (stride length 130-180 cm; stride length/height ratios of 1.36-1.66), with a large negative diagonal/ipsilateral step length ratio of À5.0 to À10.0. Though a slow rack can also set down prints in ipsilateral pairs this usually occurs at shorter stride lengths (stride length/height around 1.20) and is accompanied by an interior straddle that is close to zero or negative as hind feet can cross the center line as there is less foot interference [25,34]. Here though the interior straddle of the tracks varies from around 0.6-1.1 cm.…”

“…It may be that the mare utilized a running walk instead of a rack in order to more easily travel at a velocity matching her foal. There is a possibility that the mare employed an intermediate-speed rack which can lay down isolated prints resembling a running walk, but one would tend to expect an even more negative interior straddle (see [7,34]). Based upon our modified Alexander formula these gaits would have taken place at around 3.0-3.1 m/s for the adults (LAET-A and LAET-B) and 2.1 m/s for the foal (LAET-C).…”