Epsilon Open Archive

Abstract

There is an increasing interest in the use of physical medicine in rehabilitation of animals. The main goal in rehabilitation is to regain best possible physical function after illness or injury, by use of different physical modalities. The aim of the present investigation was to study the photothermal effects of defocused CO2 laser irradiation on equine tissue, one modality used in the rehabilitation of horses. The thesis comprises studies on the effect of irradiation on temperature, blood flow, morphology, concentration of anti-inflammatory and pain modulating mediators, and finally, lameness due to traumatic arthritis of the fetlock joint. Three experimental studies revealed that defocused CO2 irradiation (91 J/cm2) causes a moderate to vigorous heating effect (3-6 ˚C) in superficial tissues, with a concomitant increase in blood flow, detected by Laser Doppler Flowmetry. Mild to severe dose-dependent morphological changes were detected in the skin after irradiation with doses ranging from therapeutic to near-surgical (91-450 J/cm2). A clinical study demonstrated a decrease in the degree of lameness in both groups of lame horses after irradiation. No statistical difference was detected between lame horses treated with laser or placebo, evaluated by conventional lameness examination and accelerometer technique. Nor was there a difference in the concentration of inflammatory mediators such as substance P and PGE2, or the endogeneous opioid Met-enkephalin-Arg-Phe in synovia. A higher concentration of Met-enkephalin-Arg-Phe was measured in sound horses compared to horses with traumatic arthritis. In conclusion, the present thesis reveals that irradiation with defocused CO2 laser causes a moderate to vigorous heating effect in superficial tissue, and a marked increase in blood flow. The increase in temperature was of such intensity that there is a potential risk of thermal injuries to the skin. The results also suggest that treatment with defocused CO2 laser is not statistically better than placebo at reducing the grade of lameness in horse with traumatic arthritis of the fetlock joint.