Case Report: Endoscopic-guided electrochemotherapy combined with metronomic chemotherapy for the treatment of nasal tumors in dogs.

Electrochemotherapy is a local anticancer treatment used for selected cutaneous tumors, but its application in veterinary medicine for nasal neoplasms is only rarely reported. Two dogs with endonasal tumors, ineligible for radiotherapy, underwent endoscopic-guided electrochemotherapy (ECT). Each cycle included three sessions spaced 3 weeks apart. Under general anesthesia and endoscopic guidance, bleomycin (20,000 IU/m2) was administered intravenously, followed by bipolar electroporation via a new single needle electrode. Palliative metronomic chemotherapy (piroxicam, thalidomide, and cyclophosphamide) was also administered as an adjuvant to the local treatment. Both dogs showed reduced tumor size and resolution of clinical signs after the third ECT session. Only mild intraoperative bleeding was observed. Follow-up CT and endoscopy confirmed significant volumetric tumor reduction and improved nasal airflow. Endoscopic-guided ECT combined with metronomic chemotherapy appears to be a promising palliative approach for canine endonasal tumors, providing tumor cytoreduction and improvement of clinical signs. Further studies with larger sample sizes and longer follow-up periods are needed to confirm the safety and efficacy of this approach, either alone or in combination with other surgical or medical treatments.