Comparison of superficial digital flexor tendon loading on asphalt and sand in horses at the walk and trot.

This research compares how the tendon of horse legs, known as the superficial digital flexor tendon (SDFT), is loaded or stressed on different types of ground – asphalt and sand. The study found that the tendon loading is greater on sandy surface than on asphalt, particularly when the horse is trotting. This increased loading on sand is aligned with observed clinical findings in horses with SDFT injuries.

Objective of the Study

• This study aims to investigate the effect of different ground surfaces – specifically asphalt and sand – on the loading of the superficial digital flexor tendon (SDFT) in horses.
• The researchers wanted to understand if there is a variation in tendon load when horses walk and trot on different surfaces, given that SDFT injuries are one of the most common among horses and don’t seem to improved on soft surfaces like sand.

Methodology

• A total of five horses were used in the study. A non-invasive ultrasonic tendon force measurement device was used to measure and compare the SDFT loading in these horses on both surfaces at both the walk and trot.
• Three horses were equipped with the device, whereas the other two horses were equipped with the device and a dynamometric horseshoe (DHS) that helped to calibrate the values of tendon speed of sound (SOS) converted to tendon force.
• A previously established ground reaction force pattern was used to calibrate SOS measurements for the three horses without the DHS.

Findings

• Results showed that the horses were slower on the sand (S), yet the maximum tendon force was higher on sand than on asphalt when the horses were trotting (+6%). However, there was no significant difference observed between the two surfaces when the horses were walking.
• The duration of tendon loading on sand was longer (+5%) and the area under the tendon force-time curve was larger on sand (+10%) for both walk and trot.
• These findings suggest that the ground surface significantly affects the SDFT loading. The increased SDFT loading on sand aligns with clinical observations of horses with SDFT injuries, pointing to potentially higher risk associated with soft, uneven surfaces like sand.