Treatment of a Facial Myxoma in a Goldfish (Carassius auratus) With Intralesional Bleomycin Chemotherapy and Radiation Therapy

Abstract

A 4.5-year-old Ranchu goldfish (Carassius auratus) was presented for evaluation of a slowly growing facial mass of 6 months’ duration. The mass, identified histologically as a myxoma, was noted to be protruding into the oral cavity and causing exophthalmia of the left eye. Two intralesional chemotherapeutic treatments of 2.5U/kg bleomycin were performed 14 weeks apart. Reported side effects consisted of mild lethargy noted for 2 days following the second administration. Four weeks following the initial bleomycin administration, the owner appreciated a reduction in tumor size of 60%; however, tumor expansion was occurring 11 weeks following administration. Following the second administration, only 20% to 30% tumor reduction was noted and a shorter response interval of 8 to 9 weeks was noted. Two treatments with 8 Gray (Gy) fractions of megavoltage radiation were subsequently performed 4 weeks apart. The owner reported no adverse effects following treatment. However, this dosing regime was not effective at preventing tumor growth. The owner elected to euthanize the patient 23 days following the final radiation session, representing a treatment interval of 8 months after initial diagnosis. Although these treatment modalities were not successful for disease remission, they remain potentially useful treatment options for improving the quality of life in teleost patients diagnosed with myxoma.