Page 236 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Musculoskeletal system: 1.5 The hindlimb 211

VetBooks.ir on the size and location of the fracture. Small bone with evidence of inflammation, hence it is suggested
The prognosis for future athletic function depends
that trauma may be the initiating factor
fragments that can be removed arthroscopically with
minimal disruption of the articular surface carry a Clinical presentation
fair prognosis for a return to athletic function. Those The horse is generally presented because of the presence
injuries that affect large areas of the joint surface, of an unsightly mass. Owners commonly describe the
affect ligamentous attachments or lead to joint or mass as having been slowly increasing in size. The lesion
patellar instability carry a much poorer prognosis. is a firm and well-circumscribed mass closely attached
to the underlying tissues, with no involvement of the
CALCINOSIS CIRCUMSCRIPTA skin. Occasionally, horses may have a gait abnormality.
Tumoural calcinosis is a metastatic condition associated
Definition/overview with calcification of multiple periarticular sites.
This is an uncommon condition, more often seen in
young horses. The lesions involved in this condition Differential diagnosis
are usually in the subcutaneous tissue close to joints Tumoural calcinosis; osteochondromatosis; mast cell
or tendon sheaths. Although most commonly seen tumour.
in the stifle region, calcinosis circumscripta has also
been described in the hock, carpus, neck and shoulder. Diagnosis
Clinical findings are not specific enough for accurate
Aetiology/pathophysiology diagnosis. Radiography reveals localised soft-tissue
In the stifle, calcinosis circumscripta occurs on swelling and amorphous to well-circumscribed accu-
the lateral aspect close to the fibula. The cause is mulations of granular mineral opacity (Figs. 1.403,
unknown. Histologically, the lesion demonstrates 1.404). Ultrasonography is helpful to rule out other
dystrophic mineralisation of subcutaneous tissue, causes of soft-tissue swelling.

1.403 1.404

Figs. 1.403, 1.404 Caudocranial (1.403) and
lateromedial (1.404) radiographs of a horse with
calcinosis circumscripta located on the lateral aspect
of the stifle. (Photos courtesy Michael Schramme)