A 13-year-old dachshund diagnosed with cutaneous epitheliotropic T-cell lymphoma showed erythema, scales, and pruritus on the left flank. Lokivetmab was administered at 10 mg, and pruritus disappeared. The treatment was continued every 4 weeks, but pruritus returned and the skin lesions gradually worsened. The dosage was increased to 30 mg/head, and not only pruritus but also the erythema and scales disappeared. Subsequently the dosage was increased by 10 mg, and finally to 50 mg. The patient died of acute pancreatitis 769 days after the start of treatment. Lokivetmab was effective against pruritus and skin lesions in this case, and may have extended the survival time.