Introduction

Our purpose was to assess tolerance in six cases of naturally occurring tumors in dogs treated with electronic plesiotherapy and brachytherapy.

Methods

Four dogs with malignant tumors were treated with plesiotherapy via the Xoft Axxent^® system, an electronic radiation device. The plesiotherapy patients were prescribed 40Gy at a depth of 2mm to be delivered over 10 fractions in five days using the cone surface applicator. Two dogs with gross disease were treated with brachytherapy intraoperatively during the tumor excision. The brachytherapy patients were prescribed 20Gy in one fraction to be delivered to the surface of the applicator. Acute and late radiation side effects were recorded based on the Veterinary Radiation Therapy Oncology Group (VRTOG) morbidity scoring in all patients.

Results

Follow-up for patients ranged from 3 to 12 months. All patients developed acute radiation side effects with VRTOG scores ranging from 1–3. Acute side effects resolved after the end of treatment. Late side effects were assessed in 4 of the 6 patients with follow-up greater than 3 months. None of these patients had evidence of late side effects.

Conclusion

Dogs demonstrate adequate tolerance to the delivered electronic brachytherapy and plesiotherapy as a treatment modality for naturally occurring malignant tumors. The acute side effects observed in these cases are comparable to the side effects seen with strontium-90 and external beam radiation. The initial results from these 6 cases suggest that electronic brachytherapy and plesiotherapy can be helpful in controlling local tumor disease with tolerable side effects in select cases.