Page 1392 - Clinical Small Animal Internal Medicine

1330 Section 11 Oncologic Disease

of proximal appendicular tumors or disease affecting the bone can be unsightly. Tumors of the scapula may be
VetBooks.ir axial skeleton. Magnetic resonance imaging (MRI) is treated by partial or total scapulectomy with preserva-
tion of the limb; however, CT is recommended in these
generally less useful than CT for imaging bone, making
CT the imaging modality of choice in most cases. MRI
disease. Tumors of the ulna alone may be treated by
may be useful, however, in evaluating the local extent of cases to ensure adequate margins around the extent of
disease prior to limb‐sparing surgery, or to assess the ulnectomy; CT is again recommended to evaluate local
proximity of neoplasia to neurovascular structures. disease for surgical planning.
Pelvic limb tumors are most commonly treated with
coxofemoral disarticulation; similarly, this surgical tech-
Therapy nique is generally preferred over a midshaft femoral
amputation due to ease of technique and wider surgical
Surgical margins around bone and joint tumors generally margins. Tumors of the proximal femur may be treated
fall into the categories of wide or radical excision. Wide by en bloc excision of the acetabulum in addition to
excision is defined as complete removal of disease with a amputation or hemipelvectomy. Pelvic tumors can also
margin of normal tissue, and radical excision includes be treated by partial or total hemipelvectomy. When per-
the excision of a body part, such as limb amputation for forming hemipelvectomy, a detailed knowledge of
cases of appendicular neoplasia. Limb amputation fol- anatomy is important to avoid trauma to intrapelvic
lowed by chemotherapy is the recommended treatment structures such as the rectum and urethra. Preoperative
for appendicular OSA, and amputation is often indicated CT scan is indicated before hemipelvectomy, and if
for CSA, FSA, HSA, and for excision of other appendicu- incomplete or narrow surgical margins are likely, consul-
lar tumors in which local excision with adequate margins tation with a radiation oncologist prior to surgery is
is not possible (Table 150.1). The decision to pursue limb strongly recommended.
amputation is typically difficult for owners to make; Recovery after amputation surgery is generally rapid,
however, these dogs generally recover well from surgery with most dogs ambulating within a few days of surgery.
and owner satisfaction is quite high. Videos of amputee Perioperative analgesia is essential, and may be provided
dogs can sometimes be helpful to owners and are now with a wound soaker catheter or with systemically
commonly posted for public viewing on numerous web- administered medications. Recovery after hemipelvec-
sites. Dogs that are obese or have concurrent musculo- tomy surgery is similar to amputation. Complications of
skeletal or neurologic disease may have a prolonged these surgeries include seroma formation and, less com-
recovery compared to the average patient and may monly dehiscence, hemorrhage, and infection.
benefit from physical rehabilitation after surgery. Limb‐sparing surgery is described for appendicular
Tumors of the thoracic limb are preferably treated by bone tumors, but appropriate case selection and client
forequarter amputation. Forequarter amputation includ- education are essential. Limb‐spare may be indicated for
ing excision of the scapula is preferred due to the ease of cases in which the dog is unable to tolerate amputation
the surgical procedure, the likelihood of wide margins due to orthopedic or neurologic co‐morbidities, or when
around disease, and improved cosmetic appearance owners have declined amputation. In general, limb‐
when the scapula is removed, as muscle atrophy over this sparing surgery is considered only for tumors of the

Table 150.1 Treatment options for canine appendicular osteosarcoma

Treatment type Effectiveness Other considerations

Amputation + chemotherapy Gold standard; MST ~1 year Amputation generally well tolerated
Limb‐spare (SRS/SBRT or surgical) + Comparably effective to amputation + Limited availability due to highly trained
chemotherapy chemotherapy; infection associated with limb personnel required and availability of
spare surgery improves survival SRS equipment
Amputation alone MST <6 months Death due to progression of metastatic
disease
Palliative radiation Pain relief for 2–3 months >50% response rate
Aminobisphosphonates (often Four months of pain relief with pamidronate in Zoledronate more effective, may be
recommended in conjunction with 28% of dogs cost‐prohibitive
radiation)
MST, median survival time; SRS, stereotactic radiosurgery.