Clinical approach to determine the contribution of the palmar and palmar metacarpal nerves to the innervation of the equine fetlock joint.

The research explores the roles of different sensory nerves in the movement of horses’ fetlock joint by inducing lameness and applying anesthesia to different nerve sets. The study suggests that both the palmar nerves and the palmar metacarpal nerves contribute to the movement of the joint.

Introduction

• This study was conducted on horse’s fetlock joints to understand the sensory nerve supply and help determine the causes of lameness in horses. The metacarpophalangeal joint, commonly referred to as the ‘fetlock joint’, plays a critical role in a horse’s ability to walk.

Procedure

• Lameness was induced in eight horses by injecting the joint with a glycerin suspension of glass micropheres. This resulted in an observable change in the gait or way the horse walked.
• The medial and lateral palmar nerves of four horses were anesthetized. The researchers observed an improvement in the gait of the horses, but it wasn’t enough to completely eliminate the lameness.
• Following this, the medial and lateral palmar metacarpal nerves were also anesthetized resulting in improvements in 3 out of the 4 horses. They became sound, which in this context, means that they were no longer lame.

Confirmation of Results

• To confirm the findings of the local anesthesia portion of the experiment, neurectomies (a type of surgical procedure where part of a nerve is cut) were performed on a second group of four horses. This was done to determine whether severing these nerve connections would have the same effect.
• The lameness was only fully alleviated when both sets of nerves – the palmar nerves and the palmar metacarpal nerves – were resected.

Conclusion

• The results of the study suggest that both sets of nerves contribute to the sensation and movement of the fetlock joint, making them significant in understanding and potentially treating lameness in horses.