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Today's VeTerinary PracTice | January/February 2016 | tvpjournal.com elemenTs oF oncology Peer reviewed 50 An 8-year-old, castrated male golden retriever presented for evaluation of a mass on the distal femur. Non–weight-bearing lameness was present and localized to the distal femur. Complete blood count and serum biochemical profle were within normal limits. However, craniocaudal and lateral radiographs revealed a moth-eaten-appearing, lytic region within the distal right femoral metaphysis (figure 2). 1. Premedication Two hours prior to surgery: • Transdermal fentanyl liquid (2.7 mg/kg) was applied to the dorsal scapular area; the dog demonstrated mild sedation 2 hours later. • Further premedication was achieved with acepromazine (0.01 mg/kg iM), with no other opioids needed to facilitate iv catheter placement. 2. anesthetic induction Anesthesia was: • induced with propofol (1 mg/kg iv), demonstrating a noticeable propofol-sparing effect due to transdermal fentanyl and acepromazine premedication, and followed by oral tracheal intubation • Maintained with isofurane in oxygen with a circle breathing circuit. 3. intraoperative Pain Control After iv induction, but before surgical incision, an epidural was administered using bupivacaine (0.5 mg/kg) with sterile saline. A coxofemoral disarticulation was then performed. intraoperatively: • Ketamine (0.5 mg/kg bolus injection followed by 1–2 mcg/kg/min iv CRi) and lidocaine (2 mg/kg iv bolus injection followed by 5–10 mcg/kg/min iv CRi) in crystalloid fuid were administered. • Dexmedetomidine diluted in physiologic saline at 0.5 mcg/kg/H was administered as an iv CRi. • Two lidocaine patches (5%) were applied to the surgical site after skin closure. 4. Postoperative Pain Control The ketamine/lidocaine and dexmedeto- midine CRis were continued for 6 hours postoperatively. The preoperative trans- dermal fentanyl liquid, which yields 4 days of continuous analgesia, provided addi- tional pain control. The patient was ambulating, eating, and drinking normally a day after surgery, and was sent home with: • Carprofen (4 mg/kg PO Q 24 H) and tramadol (5–10 mg/kg PO Q 8–12 H) for breakthrough pain • Gabapentin (10 mg/kg PO Q 12 H) for potential neuropathic pain. if pain is not controlled with the above medications, consider other opioids, such as oTM administration of buprenorphine (120 mcg/kg Q 24 H). 5. Further Defnitive Treatment The dog was treated with chemotherapy (carboplatin, 300 mg/m2 iv Q 21 days for 4 treatments) beginning 10 days after skin sutures were removed. Five months after completion of carboplatin, thoracic radiographs revealed pulmonary nodules consistent with metastatic disease. The patient began doxorubicin chemotherapy and is currently undergoing treatment. Figure 2. right lateral radiograph of the stife showing an aggressive, bony lesion in the distal femur. Note the area of focal bony lysis at the distal femoral metaphysis that has a moth-eaten appearance (*). Following amputation, the histologic diagnosis was fbroblastic osteosarcoma. Consider This Case: Surgical Treatment of Osteosarcoma