Material and Methods
A 6-year-old female spayed Boxer was presented to the North Carolina State University Veterinary Teaching Hospital for the evaluation of an ilial chondrosarcoma (CSA).
A right hind limb lameness was noticed 4 months prior to presentation. Three months later, a firm mass was appreciated over the dog’s right ilium and one week later presented for non-weight bearing lameness. Pelvic radiographs obtained during that visit revealed an osteolytic lesion of the right ilial wing. A complete blood count (CBC) and serum chemistry panel (Chem) were performed prior to bone biopsy, which were both unremarkable. Prior to the biopsy, ceftiofur sodium (2.2 mg/kg, subcutaneously) was administered and anesthesia was induced with thiopental (11 mg/kg, IV). The biopsy results demonstrated disorganized lobules and sheets of neoplastic chondrocytes in a cartilaginous matrix. The cells exhibited moderate to prominent nuclear and cytologic pleomorphism with rare scattered mitotic figures. Histopathology was consistent with the diagnosis of chondrosarcoma. A 14-day course of amoxicillin (15mg/kg, q12hrs, orally) was prescribed. The dog was referred to North Carolina State University Veterinary Teaching Hospital for further evaluation with staging.
Upon presentation, a painful, firm, irregular mass was palpated over the right ilium and measured 5.5 inches x 4.0 inches on physical examination. A minimum database (CBC/Chem/urinalysis (UA)), urine aerobic culture, thoracic radiographs, abdominal ultrasound, and a computed tomography (CT) were performed. Blood work was unremarkable. Urinalysis via cystocentesis revealed a urine specific gravity (1.025; 1.001-1.080), 1+ bacteriuria, and 20-30 red blood cells/hpf. Therefore, the urine was submitted for aerobic culture. Urine aerobic culture grew >100,000 CFU/ml of Escherichia coli that was sensitive to all the antibiotics included within the sensitivity panel. Thoracic radiographs demonstrated no evidence of pulmonary metastatic disease. Abdominal ultrasound demonstrated a mildly enlarged spleen with no evidence of parenchymal changes and the medial iliac lymph nodes were assessed to be within normal limits.
CT of the pelvis was performed for treatment planning; the dog received hydromorphone (0.05 mg/kg, IM) as a pre-medication and induced 30-minutes later with thiopental (10 mg/kg, IV); anesthesia was maintained with 1-4% isoflurane in oxygen. An aggressive mass within the region of the right ilium body with lysis from the body of the ilium to the sacrum with medial and lateral displacement of the epaxial muscles within the region of the mass was noted (Figure 1). Given the extent of the tumor, resection with wide margins was not possible. External or internal hemipelvectomy (i.e. iliectomy) with adjuvant radiation versus palliative radiation were discussed. The owner elected to have an iliectomy performed with adjuvant radiation therapy. The patient was discharged with amoxicillin (15 mg/kg, q12hrs, orally) for the urinary tract infection and carprofen (1.7 mg/kg, q12hrs, orally) for pain management.
Two weeks later, the dog represented to North Carolina State University Veterinary Teaching Hospitalfackn for iliectomy. A fentanyl patch was applied the evening prior to surgery (100 \(\mu g/hr)\). The patient was pre-medicated with hydromorphone (0.05 mg/kg, IM) and induced with thiopental (8.5 mg/kg, IV). Anesthesia was maintained with isoflurane as before. An epidural with morphine and bupivacaine was performed prior to surgery (unknown dose). Cefazolin was administered perioperatively (22 mg/kg, IV) and repeated every 90 minutes for the duration of the surgery. The dog was placed in left lateral recumbency. The surgical site was prepared in a routine aseptic fashion with the right pelvic limb prepared for free limb draping. An eight centimeter curvilinear incision was made through the skin and subcutis three centimeters ventral to the mass. The subcutaneous tissues were dissected down to the underlying musculature. The tumor was seen to be invading the middle gluteal muscle. The middle gluteal muscle was transected caudal to the tumor with electrocautery. The body of the ilium was cleared of soft tissue and an Army Navy retractor was placed medial to the ilium to protect neurovascular structures. A sagittal saw was then used to cut through the ilium. The sacroiliac joint was disarticulated by inserting a periosteal elevator into the joint ventrally. The ilial wing and tumor were reflected dorsolaterally and removed. Remaining suspected neoplastic tissue at the disarticulation site was removed with rongeurs. A closed suction drain was placed at the resection site. A single layer of polypropylene mesh was then sutured to the fascia of the external abdominal oblique ventrally, paraspinal musculature dorsally, remaining middle gluteal muscle and tensor fascia lata caudally with 3-0 Maxon using simple continuous patterns. The subcutaneous and subcuticular layers were closed with 3-0 Maxon in a simple continuous and continuous horizontal mattress patterns, respectively. The skin was closed with stainless steel staples. During anesthesia rare ventricular pre-mature complexes were appreciated. The surgical procedure lasted 184 minutes. Carprofen was administered during recovery (2.2 mg/kg, IV). Post-operatively, the dog received hydromorphone (0.05 mg/kg, IV, PRN), acepromazine (0.02 mg/kg, IV, PRN), carprofen (1.7 mg/kg, q12hrs, orally), and amoxicillin (14 mg/kg, q12hrs, orally). Within twenty-four hours following surgery, the dog was walking and weight bearing on the surgical limb. Seventy-two hours post-operatively, the drain was minimally productive and subsequently removed by the dog. The dog was discharged with carprofen and amoxicillin for an additional ten days (same doses as previous mentioned).