Assessment of scintigraphic and thermographic changes after focused extracorporeal shock wave therapy on the origin of the suspensory ligament and the fourth metatarsal bone in horses without lameness

OBJECTIVE: To monitor the effect of focused extra-corporeal shock wave therapy (ESWT) on bone and bone-tendon junction of horses without lameness by use of nuclear scintigraphy and thermography. ANIMALS: 6 warmblood horses without lameness. PROCEDURE: The origin of the suspensory ligament at the metacarpus (OSL-MC) and the fourth metatarsal bone were treated at 2 time points (days 0 and 16) with 2,000 shocks applied by a focused ESWT device at an energy flux density of 0.15 mJ/mm2. One forelimb and 1 hind limb were treated, and the contralateral limbs served as controls. To document the effect of focused ESWT, nuclear scintigraphy was performed on days -1, 3, 16 (before second ESWT), and 19. Thermography was performed on days -1, 0 (1 hour after first ESWT), 1, 3, 8, 16 (twice; before and 1 hour after second ESWT), and 19. On days 3, 16 (first scans), and 19, thermography was performed before scintigraphy. RESULTS: Scintigraphically, significant variations in radiopharmaceutical activity at the OSL-MC were detected in treatment and control limbs. No significant differences, however, in mean temperature or radiopharmaceutical activity could be detected by use of thermography or nuclear scintigraphy, respectively, between the treatment and control limbs at any time point in response to ESWT. CONCLUSIONS AND CLINICAL RELEVANCE: After 2 treatments of focused ESWT, no physiologic effect on the studied structures could be demonstrated by use of nuclear scintigraphy or thermography. Results of this study indicate that at currently used ESWT settings, no damage to the bone or bone-tendon junction should occur.