Horse Species T 233 Velocity-related changes in stride variables of the intermediate gait of the Irish Draught horse of North America

Although originating as a farming breed having a gait derived from the bloodlines of the extinct ambling Irish Hobby horse, the Irish Draught horse today is bred to excel in the sport-horse industry. With around 500 in North America, the breed is on the Livestock Conservancy’s (LC) watch list. Study objectives were to determine the relationship between trotting velocities and stride variables. Ten Irish Draught horses selected by the LC and Irish Draught Horse Society of North America were worked at a slow velocity (SV) and fast velocity (FV) at the trot (SV = 4.5 ± 0.2 m/s; FV = 5.2 ± 0.1 m/s). Frame-by-frame analysis using the Ariel Performance Analysis System was performed documenting hoof contact and lift-off for 10 strides for each horse at each velocity with stride variables given as a % of stride duration. Means (SD) were calculated and student’s paired t-tests were performed (P = 0.05). Both velocities demonstrated a leaping diagonal footfall sequence with diagonal limb pairs at hoof contact and periods of bipedal support (FV = 79 ± 4, SV = 87 ± 3%). While neither velocity demonstrated a 4-beat rhythm at hoof contact, the diagonal limbs disassociated at lift-off (4 ± 1%) at the SV with the hind lifting first creating a period of forelimb unipedal support (9 ± 1%). Along with limb support and coupling of diagonal limbs, fore stance duration (FV = 41 ± 3, SV = 48 ± 1%), stride length (FV = 3.8 ± 0.1, SV = 3.2 ± 0.1 m/s), and length of suspension (FV = 21 ± 4, SV = 4 ± 2%) distinguished between velocities (P < 0.05). Stride duration (FV = 0.70 ± 0.01, SV = 0.74 ± 0.02 s) and rate (FV = 1.41 ± 0.02, SV = 1.37 ± 0.01 strides/sec) and hind stance duration (FV = 41 ± 4, SV = 43 ± 2%) remained consistent between velocities. The North American Irish Draught horse did not demonstrate an ambling gait at velocities measured. Nevertheless, pattern and timing of the disassociated limbs and resulting limb support are unique compared with breeds that are today used in the breeding of the Irish Draught horse such as the Thoroughbred and Warmblood, and thus, potentially reflecting gait characteristics of the extinct Irish Hobby horse.