Effects of external thermal manipulation on laminar temperature and perfusion scintigraphy of the equine digit

Aims:To assess the effects of external thermal manipulation on the soft-tis sue and Vascular perfusion of the equine digit using nuclear scintigraphy a nd documented tissue temperatures. Methods: Six horses were used in a randomised crossover design. Each horse was treated with external heat (47 degrees C) or external cold (4 degrees C ) applied to a digit for 30 minutes. The opposite front foot was untreated and used for control measurements. Nuclear scintigraphy was performed befor e, during, and after therapy to assess vascular and soft-tissue perfusion t o the digit in response to therapy. Dorsal hoof wall laminar-tissue tempera tures were recorded before, during, and after therapy using a thermistor. Results: Treatment with topical cold therapy significantly decreased soft-t issue perfusion of the digit to 80.5% of the pre-cooled values. Conversely, the application of external heat significantly increased soft-tissue perfu sion of the digit 25.1% above the pre-heated values. Vascular perfusion sho wed similar, but not statistically significant trends. External cold applic ation to the digit caused a significant mean decrease in laminar-tissue tem peratures of 11.6 degrees C during therapy, while external heat application to the digit caused a significant mean increase in laminar-tissue temperat ures of 3.9 degrees C. Conclusion: The external application of heat and cold to the normal equine foot could effectively alter soft-tissue perfusion and laminar-tissue tempe ratures within 30 minutes of treatment. The application of hot water and ic e water to the digit was a safe, well-tolerated, and economical therapy. Clinical Relevance: Cooling the foot could decrease enzymatic reactions ass ociated with laminitis, and warming could increase local perfusion when des ired.