Assessing thermal changes in the equine thoracolumbar region following different capacitive-resistive electrical transfer protocols

Natalie Calle-González^1,2*Jose-Luis L Rivero^2,3Joaquín Olivares⁴Francisco Miró³David Argüelles^2,5Francisco Requena^2,6Ana Muñoz^5,7

• ¹Department of Animal Medicine and Surgery, School of Veterinary Medicine, University of Córdoba, Equine Sports Medicine Group, University of Cordoba, Spain, Cordoba, Spain
• ²University of Cordoba, Córdoba, Spain
• ³Department of Comparative and Pathological Anatomy and Toxicology, School of Veterinary Medicine, University of Cordoba, Cordoba, Spain, Cordoba, Spain
• ⁴Department of Electronic and Computer Engineering, Superior Polytechnic School of Córdoba, University of Córdoba, Córdoba, Spain
• ⁵Department of Animal Medicine and Surgery, Faculty of Veterinary Medicine, University of Córdoba, Cordoba, Spain
• ⁶Department of Cell Biology, Physiology and Immunology, University of Córdoba, Cordoba, Spain
• ⁷Equine Sports Medicine Group, University of Cordoba, Spain, Cordoba, Spain

Capacitive-resistive electrical transfer (CRET) is an endogenous non-invasive technique, used as deep diathermy. We pursue to analyze the temperature changes by applying different CRET protocols in the thoracolumbar spine of horses, between thoracic vertebrae 15 and lumbar 2.Methods: Ten clinically sound horses without thoracolumbar pain underwent various CRET protocols applied to a standardized thoracolumbar region (T15-L2). The protocols included sham (device off), low intensity (LIP, 5%), medium intensity (MIP, 30%), and high intensity (HIP, 40%). The HIP protocol was further divided into two-subprotocols based on the application of a subsequent low-intensity capacitive therapy: HIP+CAP (with capacitive therapy) and HIP-wCAP (without capacitive therapy). Skin minimum (Tmin), maximum (Tmax) and mean (Tmed) temperatures were assessed by thermography in degrees Celsius (°C) at assigned measurement times during application, and for 30 minutes post-therapy application.Results: No significant differences in Tmed and Tmax were found between sham and LIP protocols in any of the measurement times. During application, there were no significant differences between MIP and HIP protocols, but during the first 15 min after application, Tmed and Tmax were significantly higher in the HIP+CAP protocol (median and [interquartile ranges], 29.17ºC [28.20-31.5ºC]; 31.70ºC [29.50-33.10ºC]) compared to p=0.002;]; p=0.001) and to ]; p=0.001; 28.22ºC [27.10- 29.21ºC]; p=0.004). At 30 min after CRET, Tmed and Tmax remained significantly higher in ]) compared to sham (23.16ºC [22.11-25.23ºC], p=0.022; 25.15ºC [23.12-27.10ºC]; p=0.001) and p=0.023;]; p=0.034).Main limitations: Skin temperature was measured, rather than using invasive techniques involving the insertion of thermal probes into muscles. Skin thickness and hair density may have affected temperature measurements.Conclusions: Low-intensity CRET induced similar temperatures compared to sham. Moderate and high-intensity protocols produced similar temperature increases, despite high-intensity sessions were limited to 10 minutes due to horse tolerance. Shorter high-intensity treatments may be easier to apply and adding a short time of low-intensity capacity therapy after high-intensity protocols, may help maintain elevated temperatures for longer periods of time, without significantly increasing the duration of therapy.