Clinical and pathological factors guide patient selection for electrochemotherapy in veterinary oncology in the absence of validated biomarkers.

Electrochemotherapy (ECT) is a well-established local cancer treatment that combines the administration of chemotherapeutic drugs with the application of short electric pulses to enhance intracellular drug uptake. Over the past 3 decades, ECT has become an accepted therapeutic modality in both human and veterinary oncology for the treatment of a wide range of superficial and deep-seated tumors. Although favorable response rates have been reported across many tumor types, treatment outcomes remain variable among patients and neoplasms. Currently, patient selection is based primarily on clinical and pathological factors, while validated predictive biomarkers are lacking. This review summarizes the evidence regarding factors influencing ECT response in veterinary oncology, including tumor histotype, size, local invasiveness, clinical stage, previous treatments, immunohistochemical and molecular markers, and tumor blood perfusion. Available data indicate that smaller tumors, lower disease burden, and earlier intervention are associated with improved outcomes, whereas recurrent and advanced-stage tumors show reduced responsiveness. Future research integrating molecular profiling, immune characterization, functional imaging, and liquid biopsy approaches may facilitate the development of predictive biomarkers and support a more personalized application of ECT in veterinary cancer patients.