Electrochemotherapy: potentiation of local antitumour effectiveness of cisplatin in dogs and cats.

The aim of this study was to introduce electrochemotherapy with cisplatin into veterinary medicine, where there is a need for inexpensive and effective treatment of cutaneous and subcutaneous tumours of various histological types. The response to treatment was assessed on tumour nodules in 3 cats with mammary adenocarcinoma and fibrosarcoma, and in 7 dogs with mammary adenocarcinoma, cutaneous mast cell tumour, hemangioma, hemangiosarcoma, adenocarcinoma glandulae paranalis and neurofibroma. Twenty-four tumour nodules of different size were treated; 5 with cisplatin injected intratumourally and 19 with electrochemotherapy, i.e. intratumoural administration of cisplatin followed by delivery of electric pulses to the tumour nodule. Electrochemotherapy with cisplatin had a good antitumour effect on all tumours treated. Their average size 4 weeks after treatment was also greatly reduced (0.01 cm3) compared to those treated by intratumoural cisplatin injection alone (3.0 cm3). Altogether, electrochemotherapy- treated tumours responded with 84% objective responses, whereas only one tumourpartially responded to cisplatin treatment alone. Evaluated by contingency table, the response to treatment with electrochemotherapy was significantly better than that of the cisplatin treated group (p=0.014). Furthermore, there was a significant prolongation of the duration of response in electrochemotherapy treated tumours (p = 0.046). This study showed that electrochemotherapy with cisplatin is an effective, safe and simple local treatment of different histological types of cutaneous and subcutaneous tumours in cats and dogs.