Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

584 Small Animal Radiolo g y and Ultrasono graphy
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Fig. 4-136 A 4-year-old male Cocker Spaniel had a 3-year history of lameness thought to be the
result of hip dysplasia and ruptured cranial cruciate ligaments. Swelling of the carpal and tarsal joints
was noted. A and C, Left carpal and left tarsal radiographs were obtained. A, There is soft-tissue
swelling of the left carpus and malalignment of the carpal bones, especially in the carpal metacarpal
joint. The accessory carpal bone is displaced proximally. Small erosions in the carpal bones are shown
(arrows). There is a loss of bone density in the distal radius and in the distal metaphyseal regions of
the metacarpal bones. C, There is soft-tissue swelling of the left tarsus. There is subluxation of the
tibial tarsal joint, with widening of the lateral aspect of this joint space. In the tarsal bones a generalized
loss of bone density is seen. There are bony erosions, especially on the cranial surface of the talus
(arrow). B and D, Follow-up radiographs were obtained 7 months later. B, In the left carpus the softtissue
swelling has increased dramatically. There is marked subluxation of the carpal metacarpal
joint. There are extensive erosive changes in the radiocarpal bone and in the proximal portion of the
metacarpal bones as well as in the distal radius (arrows). The accessory carpal bone is markedly displaced
proximally. There is an overall loss of bone density, especially in the periarticular regions. D,
In the left tarsus is subluxation and malalignment of the tarsal bones, especially at the proximal intertarsal
joint. There are erosive changes in the distal tibia and in the talus (arrows). Diagnosis:
Immune-mediated erosive arthritis.