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).