Nerve block and intra-articular anaesthesia of the forelimb in the sound horse.

This study investigates the effects of two types of anaesthesia, a high palmar digital nerve block (HPDN) and intra-articular fetlock joint anaesthesia (IAF), on the movement patterns of horses. The researchers found that HPDN altered the locomotion of sound horses, while IAF did not.

Objective and Method

• This study focuses on understanding the impact of two anaesthesia techniques, namely High Palmar Digital Nerve block (HPDN) and Intra-articular Fetlock Joint anaesthesia (IAF), on the movement patterns of horses. The anaesthesia techniques are commonly used in examining lameness in horses, with the assumption that they do not alter a horse’s typical locomotion. Thus, the study seeks to confirm or disprove this assumption.
• Seven Standardbred horses were used for the research. They were made to trot at a speed of 4.5 m/s on a treadmill and were recorded at 240 Hz using a ProReflex video system, both before and after the application of anaesthesia.
• The team calculated and analysed time variables, as well as segment and joint angles, to understand the effects of the anaesthesia on the horses’ movement patterns.

Results

• The researchers found significant changes in the locomotor patterns in horses subjected to the HPDN. They noted that the horses had a longer stance time and a greater range in fetlock joint angles. Additionally, they observed greater maximal pastern joint angles.
• Conversely, Intra-articular Fetlock Joint anaesthesia (IAF) did not seem to have any systematic effects on the horses’ movement patterns, as no noticeable differences in time and angle variables were observed.

Conclusion

• The findings of the study suggest that while HPDN does alter the locomotor patterns in sound horses, IAF does not. This suggests that distal limb proprioception has a significant role in normal movement, while fetlock intra-articular proprioception is apparently not as important.
• Therefore, the study highlights the need for more comprehensive evaluations to understand the effects of HPDN in lame individuals, taking into account more variables than merely the maximal overextension of the fetlock joint.