What is the most common primary bone tumor
Osteosarcoma
OSA signalment
Large-Giant breeds
Neutering status!
Bimodal distribution 1-2yr & 7-9yrs
Small dogs - axial skeleton
What is the OSA neutering status factor
2x risk of OSA in gonadectomized dogs
ROTTIES
intact = protective factor
Proposed OSA etiologies
Hormones (neutering)
Genetic - rotties, greyhound, danes, s bernard, irish wolfhound
repetitive microtraumas
molecular factors
What are some molecular facotrs
Overexpressed oncogenes: MET, TrK, HER-2
Abbreant IFG-1
Abberant mTOR signaling
Telomeralse presence
OSA presenting complaint
lameness - inflammation, micro fractures
Swelling - extra compartmental extension of tumor
OSA differntials
Chondrosarcomas
Infectious - fungal will have systemic disease
Anatomic locations
Away form elbow, towards knee 80% in appendicular skelton forelimbs 2x > hindlimb *distal radius! Metaphyseal region
OSA dx: CBC / chem
elevated ALP = bad
OSA dx: locoregion lnn assessment
5% incidence = low
OSA dx: thoracic met check vs CT
90% have micromets at Dx. missed with rads
OSA dx: FNA/Cytology
85% diagnostic accuracy - preferred over biopsy
OSA dx: Biopsy (2)
Jam shedi - worse dx, better px
Michele trephine - better dx, worse px (fractures)
OSA dx: Radiographic appreance
Aggressive bone lesions lytic, plastic, mixed codmans triangle palisading cortical bone fractures DONT CROSS JOINTS
Codmans triangle
periosteal lifting caused by subperiosteal hemorrhage
Local control
Amputation = gold standard
Limb salvage
Stereotactic radiosurgery
Amputation techniques
forelimb - forequarter technique (include scapula)
Hindlimb - coxofemoral disarticulation technique/ en bloc acetabulectomy/subtotal hemipelvectomy
Amputation results
well tolerated.
thoracic - harder balance
pelvic - harder gaining speed
Limb salvage indications
severe OA neurological disease Morbid obesity OWNER *distal radius
Limb salvage contraindications
large lesion extensive soft tissue involvement pathology fracture inappropriate location noncompliant owner advanced disease
Limb salvage locations
distal radius
digit/metacarpus/tarsus
distal ulna
scapula
distal radius salvage
preferred/most common
reconstruct w. surgical steel
Distal ulna salavage
ulnectomy.
excision of styloid process
annular ligament reinforcement
Limb salvage complications
> 50% have complications
implant failure 40%
local reoccurrence
infection >50%, 2/3 dx after 6 months
Limb salvage prognosis
good-excellent function 80%
Why is infection helpful in limb salvage
it increases the MST and met free interval y activating the immune system to be hyperactive
Stereotactic radiosurgery
entire radiation dose delivered in one treatment
min dose = 35Gy
high dose =50-60Gy
proximal humerus is best
Systemic therapeutics
Adjunct chemo
Adjunct chemo options
Carboplatin (DOC)
Bisphostphates
Amino-bisphosphates
carboplatin
monitor CBC
Starting pre, during, post op doesn’t alter efficacy
Bisphosphates
inhibits osteoclastic bone resolution
Amino-bisphosphates
Pamidronate
pain palliation 30-50%
Palliative therapeutics
RT
Analgesia
RT
50-92% response rate.
but very short duration of response
better response when <50% bone involved and proximal humerus
Analgesia
every patient should get.
NSAIDs, opioids, NMDA antagonists, anticonvulsants
Aratana
canine OSA vaccine
indevelopment
attenuated listeria monocytogenes
PROGNOSIS (KNOW THIS)
palliative analgesia- 1-3m
Surgery - 4-6m
Sx + chemo - 8-12m
Chemo alone - not recommended
Prognostic considerations
Body weight age site volume histologic grade ALP
Weight
<40kg is positive
Age
<7yrs and > 10 is positive
Site
proximal humerus is negative
Volume
larger is negative
Histological grade
3 is negative
ALP
NEGATIVE
preop increase that doesn’t decrease within 40 d
every 100U/L increase is 25% risk of death
Feline OSA
diaphysis
Pelvic > thoracic
less aggressive, slower growth
amputation may be curative