Results
Histopathological evaluation was consistent with a chondrosarcoma and
the tumor was incompletely excised as expected (Figure 2). The
chondrosarcoma was determined to be a grade II based on exhibited
moderate pleomorphism with no undifferentiated areas and 1 mitotic
figure observed per 10 high magnification
fields.23–25
As previously mentioned, the dog was scheduled to begin radiation
therapy twenty-seven days after the iliectomy. At that time, the dog had
an intermittent non-weight bearing lameness of the right pelvic limb
when running but ambulated well otherwise. Physical examination was
unremarkable other than mild pain elicited with flexion of the right
coxofemoral joint. Diagnostics included a urinalysis and urine culture
via cystocentesis, thoracic and pelvic radiographs. CT scan and
radiation therapy had to be rescheduled due to technical issues.
Urinalysis was unremarkable and the culture recovered very light growth
of Escherichia coli and Enterococcus hirae . Thoracic
radiographs revealed no evidence of metastatic pulmonary disease. Pelvic
radiographs demonstrated an overlapping fracture of the left pubic bone
as well as corresponding fracture of the left ischial arch (Figure 3).
There was evidence of callus formation over the fracture sites. Other
significant findings included mild bilateral coxofemoral and stifle
degenerative joint disease. The fractures did not appear to be causing
the dog marked discomfort; but carprofen (1.7 mg/kg, q12hrs, orally) was
prescribed.
Fifty-three days after iliectomy, the dog re-presented for initiation of
radiation therapy (nineteen 3 Gy fractions). Physical examination was
unremarkable. The following diagnostics were performed: urinalysis via
cystocentesis and culture, pelvic radiographs, and CT. Urinalysis was
unremarkable, and no bacteria were cultured. Pelvic radiographs revealed
progressive coxofemoral degenerative joint disease and healed pelvic
fractures. The fracture of the left ischium had a callus around the
fracture gap. The margins of the remaining right ilium were irregular
and consistent with healing. The mesh overlaying the right hemipelvis
region was in place. The dog was premedicated with hydromorphone (0.05
mg/kg, IM), induced with thiopental (10 mg/kg, IV), and maintained with
isoflurane. CT was acquired with 5mm slices from the cranial aspect of
L5 through the entire pelvis (Figure 4). After completion of full-course
radiation therapy the plan for re-evaluation was for physical
examination and thoracic radiographs to be performed at one month and
then every three months for two years. At the one, six, and nine month
re-evaluations pelvic radiographs were also recommended. Upon serial
re-evaluations neither pulmonary metastases nor tumor recurrence was
ever appreciated. Six months post-radiation therapy, there was
progression of new bone formation within the right hemipelvis in the
region where the hemipelvectomy was performed cranial to the coxofemoral
joint.
Between the fifteen and eighteen month rechecks, the dog was noted to
have some stiffness in her right hindlimb. Thoracic and pelvic
radiographs were performed. Thoracic radiographs were unremarkable.
Pelvic radiographs revealed mild increased new bone at the iliectomy
site and osteopenia region of the right proximal femur which was
apparent on multiple views (Figure 5). This was thought to be due to
late effects of radiation therapy causing decreased vascularity and
subsequent decreased mineralization of the right proximal femur.
Carprofen that had been discontinued around three months
post-operatively was reinstituted to help with patient comfort.
The referring veterinarian treated the dog for an abscess that had
developed at the surgical site prior to the eighteen month recheck. The
prolene mesh was removed, a drain was placed, and a course of Cephalexin
(unknown dose) was prescribed. On physical examination there was a
~8 mm open draining tract with a mild amount of purulent
discharge was appreciated at the cranial end of her scar.
At 9.5 years of age, almost 42 months post-iliectomy the dog succumbed
to a suspected cardiac arrhythmia. The dog suddenly collapsed and was
presented to a local veterinary emergency facility. Upon presentation,
the dog was tachycardic. No treatments or diagnostics were performed.
The dog was discharged with an unknown medication. The dog collapsed
again shortly thereafter and died. There was presumably no recurrence of
CSA at the time of death, however, a necropsy was not performed for
confirmation. The owner was contacted for follow-up and relayed that she
was very pleased with the outcome. The dog had some mild atrophy
appreciated on the right pelvic limb at the time of death, however,
there was no evidence of lameness or pain. Following iliectomy, the dog
was able to continue living an apparently normal life that including
running and playing.