Tendon strain in the forelimbs as a function of gait and ground characteristics and in vitro limb loading in ponies.

The study investigates the strain observed in different tendons of ponies’ forelimbs during various gaits, on different ground surfaces, and during in vitro limb loading. The results suggest that the level of strain varies depending upon the type of tendon, ground surface, as well as the presence of a rider.

Research Methodology

• The study focused on five ponies and strains on their different tendons were recorded while they walked and trotted.
• Two surfaces were used for the research – a brick pavement and sand. In each case, the horses were fitted with regular flat shoes.
• Mercury-in-Silastic strain gauges (MISS) were used to measure the strains on the tendons.
• Measures were taken from four different tendons – the superficial (SDFT) and deep digital flexor tendons (DDFT), inferior check ligament (ICL), and the suspensory ligament (SL).
• Post mortem loading of the ponies’ limbs was also done to contrast in vivo with in vitro tendon strain results.

Findings of the Study

• On a brick pavement surface, the strain in the SDFT, DDFT, and SL significantly increased when ponies transitioned from a walk to a trot. However, the ICL did not display any significant strain change.
• Comparing the two surfaces, strains in the ICL and SL were higher on pavement than on sand, while strains in the SDFT and DDFT were not significantly different across the two surfaces.
• When a pony was carrying a rider while walking on pavement, there was an increase in tendon strain in the SDFT and SL, but not in the ICL and DDFT.
• Results from post mortem limb loading tests indicated differences in the tendon strains compared to in vivo conditions. The metacarpophalangeal joint could be further extended when the elbow joint was extended during the post mortem tests.

Conclusion

• The research sheds light on the variability of tendon strain in equine forelimbs upon changing gaits, ground surfaces, and under load conditions.
• Results from the in vitro limb loading tests exhibit differences from in vivo conditions, thereby suggesting the limited value of these tests for assessing tendon functioning in living conditions.