Opioids are important for perioperative pain management due to their powerful analgesic effects, but attempts have been made to reduce opioid use through a combination of multimodal analgesia, due to the need for strict drug management, opioid induced hyperalgesia and gastrointestinal motion suppression, or the abuse of medical opioids. For this reason, local anesthesia using local anesthetics has recently attracted much attention. Compared with opioids, regional anesthesia with local anesthetics has a strong analgesic effect, and suppresses surgical stress, does not suppress respiration nor postoperative gastrointestinal motility. Furthermore, the choice of anesthesia method may affect patient prognosis because of the anti-inflammatory and anti-tumor effects of regional anesthesia with local anesthetics. The results of a large prospective study are awaited in the future to clarify clinical studies on the prognosis of tumor patients in veterinary medicine.

Non-ocular melanocytic tumor (NOMT) is rare in cats. NOMTs with high proliferative activity on the nose have been suggested to have a poor prognosis, but there is little information on treatment. We performed a nasal planectomy in a cat with a rapidly growing NOMT on the nasal planum. Histologically, the resected tumor was composed of nongranular epithelioid and spindle cells with moderate nuclear atypia and frequent mitotic figures, and it was diagnosed as a malignant melanoma. The tumor cells were near the caudal margin but were determined to be completely resected. No recurrence or metastasis was observed for more than 5 years after surgery. Nasal planectomy may be a therapeutic option for nasal NOMTs without metastasis in cats.

Mast cell tumors (MCT) are the most common malignant cutaneous tumors in dogs, but there is very little information on intramuscular MCT. Here we report a case of a surgically treated canine MCT occurring in the biceps femoris muscle. An 11-year-old spayed female labrador retriever was presented with an intramuscular mass 5.7 cm in greatest diameter located in right biceps femoris muscle. Partial resection of the biceps femoris muscle including a mass and ipsilateral popliteal lymphadenectomy were performed. The pathohistological diagnosis was MCT with incomplete surgical margin and which were detected for mutations in exons 9 of the c-kit gene. On day 8 after surgery, the dog underwent revision surgery as removal of wider area surrounding the original site, but tumor cells were not detected histologically in the re-excised tissues. No recurrence or metastasis was observed until death on 692 days after first surgery. This case indicate that partial resection of the muscle may be a treatment option for intramuscular MCT.