Photodynamic therapy: a novel promising approach for the treatment of spontaneous microbial infections in pet animals

Photodynamic therapy with full spectrum visible light and porphyrin-type photosensitisers appears to efficiently induce the inactivation of a broad spectrum of microbial pathogens, including antibiotic-resistant strains, without in turn promoting the selection of PDT-resistant species. Application of this therapeutic modality to the treatment of spontaneously developed infections in dogs resulted in a very efficient healing of wounds with an extensive drop in the population of pathogens. The treatment appeared to be applicable for both mycotic and bacterial infections and was devoid of detectable undesired side effects. No significant differences in efficacy was observed whether a porphyrin, chlorin, or phthalocyanine photosensitising agent was used in spite of strong differences in the light absorption spectrum among the three tetrapyrrole derivatives.