Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

568 Small Animal Radiolo g y and Ultrasono graphy
A
B
Fig. 4-119 A and B, A 6-month-old male Bullmastiff with forelimb lameness and muscle atrophy of
all four limbs. On physical examination some pain was noted with manipulation of the stifles. Both
shoulders and stifles were radiographed. The left stifle is illustrated. There is soft-tissue swelling of
the left stifle joint and an area of flattening involving the lateral condyle of the distal left femur
(arrows). There is no evidence of a free fragment. Diagnosis: Osteochondritis dissecans of the left
femur. A similar lesion was present in the right stifle.
the medial humeral epicondyle (Figs. 4-121 and 4-122). The anconeal apophysis usually
fuses with the remainder of the ulna around 4 months of age. A definitive diagnosis should
not be made until 41/2 to 5 months of age, because there is a certain amount of normal
variation in the time of fusion between the anconeal process and the ulna. The prognosis
is poor when secondary degenerative joint disease is present. Regardless of therapy
attempted, affected joints usually will develop significant degenerative joint disease. Both
elbows should be evaluated routinely despite the absence of clinical signs in one of the
elbows, because the condition frequently is bilateral.
Fracture or dislocation of the anconeal process may occur due to trauma or secondary
to distal ulnar physeal injury and the resultant altered growth of the radius and ulna
(see Fig. 4-122). Subluxation of the humeral-ulnar articulation will be evident in these
cases and radiographs of the entire radius and ulna will confirm the diagnosis. A theory
argues that some ununited anconeal processes are due to the asymmetric longitudinal
growth of the radius versus the ulna, resulting in stress and subluxation of the
elbow. 546,547 A counter argument is made because most cases of asymmetric growth in
breeds prone to this (e.g., Basset Hounds, Welsh Corgis) are not prone to ununited
anconeal processes. 548
FRAGMENTED CORONOID PROCESS. Fragmented coronoid process, involving usually the
medial process but sometimes involving the lateral or both processes, is difficult to diag-