An eleven-year-old MN Border Collie was presented with an ill-defined intermediate grade mast cell tumour in his right upper lip. The lesion had been biopsied by the referring veterinary surgeon and measured approximately 2.5 cm in diameter.

The local lymph nodes were normal and fine needle aspiration yielded no evidence of metastasis. Thoracic and abdominal imaging showed no evidence of metastasis.

The dog was anaesthetised and 15 mgm (15,000 i u) per sq m BSA Bleomycin was injected intravenously. After 8 minutes, the time for maximum tissue drug penetration, the tumour and 2 cm margins were electroporated using a 2.5 cm Gehl needle electrode array through the full thickness of the lip. The electrical pulses, of 1200 V/cm 0.1 msec at 1 Hz, were provided by a Cytopulse PA4000 electroporator. The dog made an unremarkable recovery. He was given meloxicam to control discomfort but showed no signs of distress and ate well.

After 2 weeks the treated site was swollen but there was no tissue necrosis. The treatment was repeated as before.

Over the subsequent 2 weeks there was necrosis of the central region of the treated site with sloughing followed by healing by granulation. The local lymph node was enlarged at 6 weeks after first treatment but subsided.

There was a small defect in the lip as a result of the treatment which the owner did not feel justified surgical reconstruction.

The dog remains disease free 10 months after treatment.