Comparison of the trotting gaits of Labrador Retrievers and Greyhounds

Objective-To compare the trotting gaits of Labrador Retrievers and Greyhoun ds to determine whether differences in locomotion are attributable to diffe rences in their manner of moving or to body size and shape differences betw een these 2 breeds. Animals-8 healthy 5-month-old Greyhounds and 5 healthy Labrador Retrievers between 6 and 18 months aid. Procedure-A series of 4 force platforms was used to record independent grou nd reaction forces on the forelimbs and hind limbs during trotting. Values of stride parameters were compared between breeds before and after normaliz ation for size differences. Standard values of absolute and normalized stri de period and stride length were determined from linear regressions of thes e parameters on relative (normalized) velocity. Forces were normalized to b ody weight and compared at the same relative velocity. Results-Greyhounds used fewer, longer strides than the Labrador Retrievers to travel at the same absolute speed. After normalization for body size dif ferences, most measurable differences between breeds were eliminated. Subtl e differences that did persist related to proportion of the stride that the forefoot was in contact with the ground, timing of initial hind fool conta ct relative to initial forefoot contact, and distribution of vertical force between the forelimbs and hind limbs. Conclusions and Clinical Relevance-Results suggest that apparent difference s in the trotting gait between Labrador Retrievers and Greyhounds are mainl y attributable to differences in size, and that dogs of these 2 breeds move in a dynamically similar manner at the trot.