Pelvic fractures are relatively common in horses and ponies and can occur as a consequence of trauma or stress from athletic training. Fractures involving the acetabulum almost always occur as a consequence of trauma and usually present as a severe lameness, which is frequently non-weight-bearing at the time of injury. Crepitus may be difficult to appreciate, even during passive flexion of the limb or rectal examination. Radiography can be diagnostic, but the difficulties of obtaining such images means that diagnosis is usually achieved by a combination of nuclear scintigraphy and ultrasonography. In particular, ultrasound diagnosis of pelvic fractures has advanced considerably and is now considered the first-line method to assess pelvic fractures. Fractures of the acetabulum, in contrast to other types of pelvic fractures, carry a poor prognosis for return to athletic function, because such fractures are frequently displaced and invariably lead to osteoarthritis. The only treatment is usually prolonged (6–9 mo) rest followed by symptomatic therapy for any resultant osteoarthritis.