Electrochemotherapy of horses. A preliminary clinical report.

Sarcoids are skin spontaneous tumours detected in horses. It can be cured by chemotherapy by using cisplatin. A multisequence treatment must be performed. Problems are present due to the poor diffusion of the hydrophilic product in the tumours. Electropulsation is known to drastically enhance the effect of antitumoral drugs in vivo. Taking into account the very successful results of the group in Ljubljana (Slovenia), we started a research clinical program where electropulsation was applied after local cisplatin injection. The size of sarcoids is large (several centimeters). A specially designed set of wire contact electrodes was built. The distance between the electrodes was 0.9 cm and their length was 0.9 cm. The contact with the skin was obtained by a conductive paste. A PS15 Jouan Electropulsator was used to deliver eight pulses of 0.1 ms at a 1-Hz frequency with a 1.3-kV voltage. The animal was anesthesized. Intratumoral cisplatin injections were operated every 0.6 cm (0.2 ml at a 1-mg/ml concentration). Five minutes after the first drug injection, multiple electrotreatments were applied by moving the electrodes between the pulse applications. This allows the treatment of all the tumour surface. Several successive treatments were performed with a delay of 2 weeks between each. All lesions completely responded. The sarcoids disappear after only 2 or 3 electrochemotherapies. Objective responses were obtained in 100% of the treated lesions. All horses tolerated the treatment well. No adverse effect from the electric pulses was observed even in the case of a high number of pulses, or when several consecutive treatments were applied. No regrowth was observed in the 18 months follow-up period.