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Musculoskeletal system: 1.7c The axial skeleton – pelvis 281

VetBooks.ir published study), with a variable degree of lame- Mares with fractures of the pubis or ischium may
have vaginal or vulvar swelling from oedema
ness, depending on the location of the fracture
and its duration. Fractures of the ilial shaft or ace-
if a major artery is severed by the sharp edges
tabulum commonly produce a non-weight-bearing and haemorrhage. Fatal haemorrhage can occur
lameness, although horses with other types of pel- of the displaced bones, particularly in ilial shaft
vic fracture may be as lame. The lameness is com- fractures.
monly evident at the walk. Fractures of the sacrum
or pubis commonly result in bilateral hindlimb Differential diagnosis
lameness, and horses with fractures of the acetab- Fracture of the femur; separation of the femoral head;
ulum have an extremely short limb protraction at coxofemoral luxation; exertional rhabdomyolysis.
the walk. Pelvic asymmetry is common with frac-
tures of the tuber coxae and complete fractures Diagnosis
of the ilial wing or shaft. Fractures of the tuber Diagnosis is based on history, clinical signs, findings
coxae frequently present with unilateral lameness on external and rectal palpation, and imaging.
and painful swelling over the affected bone with,
or without, palpable crepitus. Fractures of the Imaging
tuber ischia usually show asymmetrical position- Radiography of the pelvis is easily performed in a
ing and swelling (Fig. 1.529). Other clinical signs foal, but is considerably more difficult in the adult
may include muscle spasm, subcutaneous haema- horse. Most fractures can only be imaged with the
toma and, occasionally, penetration of the skin horse under general anaesthesia (Fig. 1.531). Due
by the sharp edges of the fractured bone. While to the risk of further damage or displacement during
complete fractures of the ilial wing in a racehorse recovery, this is contraindicated. A technique has
may be present on one side only, signs of subclini- been described for obtaining images of the caudal
cal stress fractures in the same site on the contra- ilial shaft, femoral head and greater trochanter,
lateral limb are commonly reported (Fig. 1.530). acetabulum and coxofemoral joint in the standing

1.529 1.530

Fig. 1.529 View from the left side of a chronic Fig. 1.530 This 6-year-old Thoroughbred racehorse
left ischial fracture showing asymmetry of outline has bilateral ilial wing stress fractures. Note the way the
of the left and right tuber ischia. The pull of the horse is standing with the hindlimbs tucked underneath
thigh muscles displaces the fracture distally. the body and the pelvis appearing to be more vertical in
(Photo courtesy Graham Munroe) orientation than normal. There was palpable pain over
both ilial wings. (Photo courtesy Graham Munroe)