Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

548 Small Animal Radiolo g y and Ultrasono graphy
A
B
Fig. 4-94 A 9-month-old male German Shepherd dog with a right foreleg lameness and pain on
palpation of the right humerus. Pain was also noted on extension and flexion of the right shoulder.
Initial (A) and 4-month follow-up (B) radiographs of the right humerus are illustrated. There is an
increase in medullary density within the entire diaphysis of the right humerus, with mild periosteal
proliferation on the cranial and caudal surfaces of the humeral diaphysis. Flattening of the proximal
humeral head (arrow) with sclerosis in the subchondral bone is present. This is indicative of panosteitis
and osteochondrosis. In the follow-up radiograph, the increased right humeral diaphyseal density
has resolved. Several fine linear densities are present in the middle and distal portions of the
humeral diaphysis. The cortical density and thickness are normal. There is a slight residual flattening
in the proximal humeral head (arrows). Diagnosis: Panosteitis and osteochondrosis.
to progress toward the diaphysis as the dog grows. The physis and epiphysis usually are not
involved (Figs. 4-95 and 4-96). Although the condition disappears with maturity, a residual
bowing deformity of the forelimbs may result and mild thickening of the metaphysis may
remain. Some deaths have been reported in dogs with hypertrophic osteodystrophy.
Many normal, rapidly growing, young, large-breed dogs have mild irregularities and sclerosis
of the proximal and distal ulnar, radial, and tibial metaphyses. This must be considered
when evaluating a dog suspected of having hypertrophic osteodystrophy. 397 The line of
demarcation between normal and mild hypertrophic osteodystrophy is indistinct.
Hypertrophic osteodystrophy and craniomandibular osteopathy have been reported
simultaneously in a few large-breed dogs. Some Terriers affected with craniomandibular
osteopathy have had long bone changes resembling hypertrophic osteodystrophy. 403
H Y P E RT R O P H I C O S T E O PAT H Y
Hypertrophic osteopathy produces a generalized, symmetric, palisading periosteal proliferation
that involves the diaphyses of the long bones (Figs. 4-97 and 4-98). The condition
most often is associated with either infectious or neoplastic intrathoracic lesions (i.e.,
pleural, pulmonary, cardiac, and mediastinal); however, hypertrophic osteopathy has