Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

Chapter Four The Appendicular Skeleton 551
Fig. 4-99 A 10-year-old mixed breed female dog was brought in for
treatment of mammary gland tumors. Bone lesions were noted on
the thoracic radiographs and survey radiographs of the limbs
obtained. A lateral radiograph of the left humerus is illustrated; however,
similar lesions were present in the front and rear limbs. Multiple
punctate densities are present through the humeral diaphysis and
metaphysis. Diagnosis: Bone infarcts. Although these are often associated
with sarcomas of bone, none was identified in this dog.
been reported in association with bladder, liver, and ovarian tumors without thoracic
disease. 404-419
The periosteal proliferation becomes more extensive as the disease progresses. The
bony proliferation usually affects the distal portions of the limbs more severely; however,
involvement of the proximal portion also may be observed. The tarsal and carpal bones and
abaxial surfaces of the second and fifth metatarsal and metacarpal bones are involved most
often. The periosteal proliferation usually is irregular and oriented perpendicular to the
cortex, but it may also be smooth and oriented parallel to the cortex.
The limb swelling and periosteal proliferation may be the earliest sign of an asymptomatic
thoracic lesion. Regression of the bony proliferation occurs after treatment of the
primary disease, but the bones remain abnormal for a long time.
B O N E I N FA R C T S
Bone infarcts are areas of necrosis within the medulla. Bone infarcts appear radiographically
as multiple, irregularly demarcated, distinct intramedullary densities in one or several
bones (Fig. 4-99). Usually there are no clinical signs directly associated with the infarcts.
Bone infarcts may be seen in conjunction with sarcomas. However, whether or not they
represent a cause or effect is unclear. 148,149,158,420-423
JOINT DISEASE
Radiography aids in diagnosis, prognosis, and monitoring the response to therapy in
patients with joint disease. 424-435 The radiographic findings usually indicate a general
category of joint disease (e.g., degenerative, infectious, neoplastic, immune mediated) and
not a specific entity.