Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

504 Small Animal Radiolo g y and Ultrasono graphy
Fig. 4-35 A 14-month-old male mixed breed dog had an open
comminuted fracture of the right tibia repaired 1 month previously.
An intramedullary pin is present, and extensive bony proliferation
involves the proximal and distal fragments. There is a
very dense, sharply marginated fragment in the midportion of
the tibia. The bony proliferation surrounds but does not contact
or involve this bony fragment. There is irregular reabsorption of
bone surrounding the intramedullary pin and diffuse extensive
soft-tissue swelling. Diagnosis: Osteomyelitis and lack of bone
healing (delayed union) due to infection and a sequestrum. This
fracture was successfully treated by removal of the sequestrum and
intramedullary pin and administration of systemic antibiotics.
Fig. 4-36 A 3-year-old neutered male mixed breed dog had
been hit by a car and fractured his right femur. The fracture was
repaired with an intramedullary pin. Eight weeks after surgery
the dog’s leg became painful and developed a draining tract. A,
The anteroposterior view reveals a great deal of callus formation,
especially on the medial aspect, that is mostly remodeled. A
small, radiodense structure (sequestrum) immediately medial to
the intramedullary pin is surrounded by a small zone of lucency
(involucrum, arrows) that contains a very dense, well-defined
small bony structure (sequestrum). B, The lateral view reveals
the clearly defined, sharp-edged and angular, increased-density
fragment (sequestrum) surrounded by the relatively radiolucent
involucrum (arrows). Diagnosis: Sequestrum formation.
A
B