Effects of a 2-week treatment with pulsed monochromatic light in healthy pigs: a clinical and morphological study

Background: Pulsed monochromatic light (PML) is now used clinically for pain relief and wound healing in both human and veterinary practice. The purpose of this study was to evaluated the clinical and pathological effects of PML irradiation in an animal model, using healthy specific pathogen-free pigs. Methods: After 2 weeks of habituation, one group of animals (n=9) underwent treatment with pulsating monochromatic infrared and red light while the control group (n=9) was left untreated. PML was given five times a week during a 2-week period, and at each treatment the total radiant exposure was 6.3 J/cm(2). At the completion of the study, all pigs were subjected to complete necropsy, Results: None of the animals showed any clinical signs of disease during the study period. The measured hematological and clinico-chemical variables all showed values within the reference range and the daily weight gain was high in both the treatment and control groups (825 and 923 g/day, respectively). The pathological examination revealed no morphological differences between treated and non-treated animals. Conclusion: In healthy pigs, no adverse effects of low-energy photon therapy on the clinical state of health or on the morphology of different tissues were observed.