Does an increase in body weight influence the sagittal and carpal range of motion in Shetland ponies at walk and trot?

Abstract

Obesity is becoming an important disease in both men and animals in western countries. It has already been shown in man that obesity would significantly modify gait into shorter strides, wider steps with a reduced range of distal limb motion. Only little research, however, has been done on the influence of a high body condition on the gait of animals. Especially in Shetland ponies, known as a breed being prone to obesity. Therefore, in this study the sagittal range of motion (SROM), the carpal range of motion (CROM) and the stride duration (StriDur) of a group of (n=11) adult Shetland ponies at walk and trot were analysed by using an inertial measurement unit (IMU) sensor based system. The ponies in the intervention group (n=7) received a 200% maintenance DE diet and in the control group (n=4) a 100% maintenance DE diet. Within the intervention group the stride duration decreased significantly at trot (0.60s vs 0.45s; P<0.05) and the SROM increased significantly at both walk (67.5° vs 71.2°; P<0.05) and trot (68.6° vs 72.9°; P<0.05). There was no significant difference in SROM between the groups and within the control group; likewise CROM did not significantly change between and within both groups. In conclusion, obesity tends to shorten gait in ponies while showing more SROM. This could be of clinical relevance since obesity contributes to several overweight-based orthopaedic diseases, such as osteoarthritis and, particularly in Shetland ponies, laminitis.