Effects of analgesia of the distal interphalangeal joint and navicular bursa on experimental lameness caused by solar pain in horses.

This research article investigates whether pain in a horse’s hooves, specifically on the upper border of the sole, can be reduced by numbing either the horse’s distal interphalangeal joint (DIP, essentially a joint in the horse’s leg) or the navicular bursa (NB, a small sack located on the bottom of the horse’s foot). The researchers generated a model of lameness in horses by applying pressure to this area, and then used either a local anesthetic or saline to numb the DIP joint or NB. They found that the anesthetic significantly reduced the lameness compared to saline, suggesting that such numbing treatments might be beneficial for horses experiencing hoof pain.

Introduction and Methods

• The study is based on the hypothesis that pain originating from the upper border of a horse’s hoof sole can be relieved by analgesia (numbing through medication) of either the distal interphalangeal joint (DIP) or the navicular bursa (NB).
• To test this hypothesis, the researchers established an induced lameness model in six horses. They caused pain by applying pressure to the dorsal margin of the hoof sole using set screws fastened to the horse’s shoe.
• The horses’ movements, or gaits, were recorded both before and after the screws were applied. Subsequently, either a local anesthetic or saline was administered to the DIP joint or the NB, and the horses’ gaits were again recorded.

Data Collection and Analysis

• Two clinicians, who were blinded to the treatment the horses received, independently evaluated and scored the gait of the horses. The scoring done was semi-quantitative, meaning that it was based on a mixture of numerical values and subjective assessment.
• The researchers observed that lameness scores were high following the application of screws. When saline was given, lameness scores continued to be high. However, when local anesthesia was given, there was a significant reduction in lameness scores, as indicated by statistical testing (P < 0.05).

Conclusion

• This paper concludes that both the DIP joint and the NB seem capable of desensitizing a part of the sole. Therefore, when it comes to diagnosing the cause of lameness in horses, pain from the upper border of the sole should not be disregarded as a potential cause if lameness decreases when either the DIP joint or the NB is numbed.