Shock Wave: No Analgesic Effect Found in Study

Extracorporeal shock wave therapy (ESWT) does not appear to improve lameness in horses with chronic pain in the proximal palmar metacarpal/plantar metatarsal area, but researchers maintain that banning ESWT before competition to prevent or minimize the occurrence of catastrophic injuries is a sensible precaution until further research is performed.

ESWT is widely used to treat proximal suspensory desmitis (inflammation of the suspensory ligament). It is thought to improve lameness by inducing the release of cytokines (inflammatory mediators) that can result in tissue remodeling. But some research suggests it can also result in an analgesic effect. Because of this, most racing jurisdictions do not permit the use of ESWT immediately prior to competition.

To further investigate this, Michael Weishaupt, DMV, from the Equine Hospital at the University of Zurich in Switzerland, co-authored the recent study, "Short term analgesic effect of extracorporeal shock wave therapy in horses with proximal palmar metacarpal/plantar metatarsal pain."

Weishaupt and colleagues evaluated the analgesic effect of ESWT, as well as the impact of ESWT on lameness due to chronic pain in the proximal suspensory ligament region of 16 horses.

Horses were sedated and treated using an electrohydraulic shock wave generator. Two thousand pulses were applied to the origin of the suspensory ligament on the affected limb.

No significant improvements in stride frequency, stance duration, vertical impulse, or peak vertical force were noted at six, 24, 48, or 72 hours following treatment.

Based on these results, the authors suggest that a single session of ESWT does not appear to improve lameness by causing an immediate analgesic effect. Nonetheless, the authors acknowledge that due to the short term follow-up period, the limited number of horses included in the study, and the lack of a control group in this present study, additional research is needed.

In the interim, the study authors do not recommend lifting the ban on the use of ESWT before athletic events simply based on the results of this study.

This study was published in volume 179 (2009) of The Veterinary Journal.

About the Author

Stacey Oke, DVM, MSc

Stacey Oke, MSc, DVM, is a practicing veterinarian and freelance medical writer and editor. She is interested in both large and small animals, as well as complementary and alternative medicine. Since 2005, she's worked as a research consultant for nutritional supplement companies, assisted physicians and veterinarians in publishing research articles and textbooks, and written for a number of educational magazines and websites.

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