A NOVEL APPROACH TO THE TREATMENT OF CAUDAL HEEL PAIN USING EXTRACORPOREAL SHOCK WAVE THERAPY

Anecdotally, extracorporeal shock wave therapy (ESWT) is widely used in equine practice to treat a variety of musculoskeletal conditions. The therapy has been used to treat caudal heel pain of the forelimbs, a common, chronic, degenerative condition that causes lameness. The objectives of this study were to characterize the use of ESWT among equine practitioners in North America, and following this, to determine the analgesic efficacy of focused ESWT on horses with naturally occurring caudal heel pain and the effect of this therapy on the appearance of lesions diagnosed by magnetic resonance imaging (MRI) in the same group of horses. A 21-question online survey was conducted to evaluate equine practitioners' rate of use, indication for use, and opinion of efficacy and tolerability of ESWT for their equine patients. ESWT was used frequently by 65/144 (45.1%) respondents, infrequently by 61/144 (42.4%) respondents, and never by 18/144 (12.5%) respondents. The most common reason for use was to treat ligamentous injuries. Overall, the therapy was rated as a moderately effective option for various musculoskeletal conditions of the horse. In the second experiment, 49 limbs (11 unilateral, 19 bilateral; 30 horses total) were examined using subjective lameness evaluation, kinematic gait analysis, and MRI. Following randomization, fifteen horses with naturally occurring caudal heel pain were treated with focused ESWT under standing sedation, and fifteen horses received no treatment but standing sedation. Outcome measures included change in subjective lameness grade of each limb, total lameness score of each horse, absolute change in kinematic gait analysis measures, and change in MRI grades for each included limb from day -16 to day 128. The results indicated that focused ESWT decreased subjectively assessed pain in horses with unilateral caudal heel pain for at least 128 days (p=0.049). No significant differences were noted in kinematic gait analysis variables between groups. Horses treated with ESWT experienced a worsening of navicular bursitis (p=0.027). In summary, based on the response to treatment with ESWT, we are unable to firmly recommend the therapy for horses with caudal heel pain at this time. Some horses may experience analgesia that may not be related to improvement of the lesions within the foot