Photodynamic antimicrobial and antineoplastic therapy in veterinary medicine: current status, challenges, and perspectives.

Significant causes of morbidity in veterinary medicine are tumourigenic diseases and pathogenic infections, which pose significant threats to animal health. Traditional methods for treating tumours and bacterial infections primarily involve chemotherapy and antibiotic therapy, both of which are associated with drug resistance and adverse effects. Photodynamic therapy (PDT) is gaining increasing interest in veterinary clinical practice because of its distinctive benefits such as spatiotemporal selectivity, low toxicity, fewer negative effects, and reduced risk of drug resistance. This review summarises the fundamental principles of PDT and its applications in combating tumours and microbial infections in veterinary practice involving companion animals, livestock, wildlife, and reptiles. It is worth noting that the existing clinical evidence is limited by very small sample sizes and the absence of comparator groups; however, these studies have provided a preliminary theoretical foundation and technical reference for further clinical development of PDT. Moreover, the opportunities and challenges associated with PDT in veterinary clinical practice are discussed herein.