Page 174 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Musculoskeletal system: 1.4 The forelimb 149

VetBooks.ir 1.273 1.274

Fig. 1.273 Two-year-old Thoroughbred racehorse Fig. 1.274 Dorsomedial/palmarolateral oblique
in dorsal recumbency under general anaesthesia about radiograph of the cannon region of a young
to have arthroscopic surgery of its intercarpal joints. Thoroughbred horse showing a dorsolateral third
Note the extreme bony swellings on the dorsal aspect metacarpal stress fracture. Note the obliquely running
of both cannon bones caused by bucked shins. (Photo fracture line in the dorsolateral cortex (arrowhead)
courtesy Graham Munroe) and the smooth periosteal new bone (arrow).

Diagnosis Management
Diagnosis can be suspected through history, sig- Since the condition is related to training intensity,
nalment and physical examination. Radiography review and alteration to training is advised. In mild
may confirm findings and show evidence of dorsal cases this may be enough, and the horse can continue
metacarpal disease of varying degrees from soft- training. In moderate cases a period of rest, NSAIDs
tissue swelling and irregular periosteal new bone to and local treatment (in the acute phase, cold therapy
oblique radiolucent lines consistent with dorsal cor- for example) may be required. In persistent cases of
tical stress fracture (Fig. 1.274). The latter is usually non-responsiveness to management changes, extra-
at a 30–40 angle to the cortex, extending proxi- corporeal shock-wave therapy has been used suc-
o
mally (occasionally distally) through about 60% of cessfully. Surgical management includes osteostixis
the bone. Rarely, the radiolucent line continues and combined with screw placement in the dorsal cortex.
curves back to the surface to form a ‘saucer’ frac-
ture configuration. Nuclear scintigraphy is a sensi- Prognosis
tive measure of bone turnover, showing increased The outcome for horses with dorsal metacarpal dis-
uptake in the dorsal metacarpus in affected cases ease following management changes is generally
(Fig. 1.275). good.