Evaluation of analgesia resulting from extracorporeal shock wave therapy and radial pressure wave therapy in the limbs of horses and sheep.

The study examines the effectiveness and mechanisms of extracorporeal shock wave therapy (ESWT) and radial pressure wave therapy (RPWT) in providing pain relief in the limbs of horses and sheep.

Study Design and Methodology

• The researchers used an electrical stimulus to establish the pain threshold for each horse for three days prior to the treatments—the ESWT and RPWT. This was done in order to acquire baseline data.
• The stimulus was again administered eight hours after the treatment, and then — at 24-hour intervals for the next seven days.
• The tests included a treatment field (midmetacarpus or midmetatarsus) and a nerve field located distal to a treatment site containing the nerve on the abaxial surface of the proximal sesamoid bone.
• All four limbs of each of 30 sheep were also treated by either ESWT, RPWT, or a sham treatment. Two sheep were euthanized each day and their tissue was harvested for histologic evaluation. The concentrations of two types of neuropeptides, substance P and calcitonin gene-related peptide, were also measured in the skin and periosteum.

Findings

• The study did not find any significant differences between the baseline data and the data gathered after treatment for either field of treatment or nerve field sensation.
• A significant change in the slope was observed when the data for horses was plotted for the first three days after treatment, compared to days four through seven post-treatment. This suggests that there might be a change in response over time after receiving treatment.
• There were no differences found in the concentration of neuropeptides after treatment in sheep, but an inflammatory response was detected in the treated nerves.

Conclusion

• The research concludes that a small cutaneous analgesic effect may occur at the site of treatment for about three days following either ESWT or RPWT in horses.