Page 203 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

178 CHAPTER 1

VetBooks.ir 1.341 and dorsally. Concurrent fractures may be pres-
ent, and evidence of dysplasia may also be noted.

Management
Manual reduction under general anaesthesia is pos-
sible, particularly in smaller breeds. Recurrence
is common and scapulohumeral arthrodesis is
described for management of these cases.

Prognosis
The prognosis is guarded following reduction of
shoulder subluxation and cases often develop OA.
Horses undergoing scapulohumeral joint arthrodesis
are left with residual mechanical lameness.

HUMERAL FRACTURES

Definition/overview
Humeral fractures include fractures of the diaphy-
Fig. 1.341 Schematic drawing of the equine humerus sis, deltoid tuberosity, greater tubercle, and stress
showing the common locations of stress fractures. fractures.

1.342 Aetiology/pathophysiology
Most humeral fractures are caused by external
trauma (e.g. kick or fall). Fractures can be complete
or incomplete, transverse, spiral, oblique or commi-
nuted. Due to the forces involved in humeral frac-
tures and the shape of the humerus, most cases tend
to be complete spiral or oblique fractures. Stress
fractures tend to be at the proximocaudal, distal cra-
nial or caudal humerus (Fig. 1.341). Deltoid tuber-
osity fractures are generally due to external trauma.

Clinical presentation
Affected horses tend to show an acute severe lame-
ness. Complete humeral fractures show instability and
loss of limb function. Horses with stress fractures may
show moderate lameness but often few other clinical
signs. These horses may progress to complete fractures
if not diagnosed early. Horses with deltoid tuberos-
ity fractures usually have evidence of external trauma
(e.g. wound), with pain/crepitus over the affected
region, but are able to bear weight (Fig. 1.342).

Fig. 1.342 Swelling over the upper forearm and Differential diagnosis
shoulder region due to a non-displaced fracture of the Ulna fracture; scapula fracture; radial neuropathy;
proximal humerus. (Photo courtesy Graham Munroe) brachial plexus injury.