Relationship Between Velocity and Step Parameters for the Stepping Gait of Leash Led Large-Breed Dogs

Canine lameness evaluation in the clinical setting consists of visually assessing the gait of the dog as the owner walks the dog on a leash. Nevertheless, research has shown that different handlers and handler position can influence walking gait mechanics in small dog breeds, but further research specific to the leash led gait as it relates to large dog breeds is limited. The objective of this study was to determine the relationship between velocity and step parameters of large-breed dogs being led at a stepping gait. Six dogs classified as large dog breeds (weight: 29±4 kg) that were determined to be clinically sound according to veterinary evaluation were led by the same handler positioned on the same side of the dog at a slow (s=1.3-1.5 m/s) and fast (f=1.8-2.0 m/s) stepping gait. Gait inclusion required a stride phase free of suspension, gait consistency with velocity maintained at ranges comparable to a large-breed trot, and noticeable paw placement and lift-off. Step parameters determined by frame-by-frame analysis with video frames of paw placement and lift-off documented. Step parameters given as a % of stride. Means (SD) determined for step parameters and t-tests (P<0.05) performed between velocities. Although both stepping gaits demonstrated a lateral footfall sequence, stride duration decreased with increasing velocity (s=0.54±0.05 msec, f=0.40±0.02 msec; P<0.05) as stride length remained consistent (s=0.79±0.04 m, f=0.81±0.07 m; P>0.05). Both gaits alternated between bipedal and tripedal support phases (s=11±1%, f=15±3%; P>0.05). Nevertheless, as velocity increased the primary support phase transitioned from a lateral bipedal (s=63±4%, f=35±3%; P<0.05) to a diagonal bipedal (s=26±2%, f=50±5%; P<0.05) support phase. The majority of stride was spent in the stance phase for both velocities (s= fore-50±1%, hind-61±3%; f= fore-58±2%, hind-58±4%), but the slower velocity demonstrated a significant difference between the fore and hind stance durations (P<0.05). Typically, with increasing velocity a dog will add a period of suspension to conserve energy and increase distance covered, but when this addition is restricted by the handler, as performed in this study, the large-breed dog utilizes changes in stride and stance durations along with limb support to achieve the faster velocity. The lack of influence on stride length to increase velocity as seen in this study may be restricted by the stride length of the handler, particularly in a large-breed dog, and thus, this may need to be a consideration when selecting handlers for gait assessment.