Effects of heel and toe elevation upon the digital joint angles in the standing horse.

This study investigates how varying the orientation of a standing horse’s foot, particularly through heel and toe elevation, impacts joint angles within the horse’s lower forelimb. The findings suggest that adjusting the horse’s foot orientation has significant effects on these angles and can potentially influence tendon tension, implying potential impacts on equine health and mobility.

Methodology

• The study involved five adult horses aged between 8-14 years, all of which had toe angles between 45.5-55.0 degrees.
• Horses were placed on a specialized platform that facilitated seven different conditions of foot orientation: neutral position, and 5, 10, and 15-degrees heel and toe elevation.
• By using the platform, only the horse’s left forelimb was weightbearing.
• Two different sequences were utilized to orchestrate these conditions.
• For each condition, two lateromedial radiographs were taken to measure the angles of the metacarpophalangeal joint (MPJ) and both interphalangeal joints (PIPJ and DIPJ).
• Two-dimensional kinematic data was also collected using reflective markers placed on the horse’s left forelimb joints.

Results

• The condition of the foot had a clear, statistically significant impact on all joint angles (JA) and their variations from the neutral condition.
• The sequence of conditions didn’t influence these differences.
• The joint angles showed linear relationships with the conditions and the effect was overall similar for the three joints examined.
• The widest range of changes in joint angle, from extreme toe to heel elevation, was 6.9 degrees for the MPJ, 7.3 degrees for the PIPJ, and a larger 29.5 degrees for the DIPJ.
• Despite variations in hoof structure, angular variation (AV) exhibited no significant differences across the horses.
• There were notable differences between joint angles measured through radiography and those measured from kinematics, possibly down to skin movement.
• Heel elevation caused a slight movement in the horse’s elbow joint, whereas toe elevation caused a slight extension.
• These minimal shifts in the elbow angle may impact the tension in the flexor tendons.

Conclusion

• The study demonstrates that changes in foot orientation, caused by different degrees of heel and toe elevation, substantially affect the joint angles in a horse’s lower forelimb.
• This highlights the need for careful decisions when making hoof modifications to horses, given the significant biomechanical implications that even minor changes may have on the animal’s overall health and movement.