EQUINE VETERINARY EDUCATION / AE / SEPTEMBER 2017


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peracute phase. Swelling as a result of haemorrhage may follow. Horses usually will load the limb. Fractures of the third trochanter also have been recognised in horses in training and racing and are thought to be the result of traction injury. However, these do not generally present on the racecourse and more usually are discovered in subsequent lameness investigations.


Pelvic fractures Fractures of the pelvic girdle are common and potentially life threatening training and racing injuries. The vast majority of fractures of the pelvis that occur during racing or training are stress related injuries and as such have predilection sites (Shepherd et al. 1994; Pilsworth 2003). Occasionally, fractures of the pelvic girdle will result from falls or other on course trauma such as injury in starting stalls. The ilial wing is one of the commonest site of stress fracture in skeletally immature Thoroughbred racehorses (Pilsworth 2003). These may be unilateral or bilateral with varying degrees of limb dominance. Fractures can be complete or incomplete in dorsoventral and craniocaudal planes. Complete fractures exhibit varying degrees of displacement determined principally by fracture location and configuration. Fractures of the ilial wing that present on the racecourse usually are complete and frequently displaced. Trauma to dorsally lying gluteal or caudally positioned iliolumbar arteries (Fig 19) will result in varying amounts of haemorrhage into overlying muscle masses. This may be visible as a protuberance or increased convexity at this site. Affected animals frequently are in marked pain but the amount of haemorrhage rarely is life threatening. Classically, horses that have suffered pelvic fractures exhibit intense muscle spasm and guarding of the affected hindquarter. Asymmetry of osseous landmarks is indicative of fracture displacement but caution must be exhibited as postural abnormalities, soft tissue swelling and muscle atrophy can be misleading. Additionally, the longevity of asymmetry always must be questioned. As determined by location, displaced fractures of the ilial wing may result in displacement of the tuber sacrale or tuber coxa. When unilateral, the tuber sacrale frequently is ventral to its intact counterpart. Firm downward pressure at this site often is resented (Shepherd et al. 1994). Displacement of the tuber


Gluteal


coxa, presumably as a result of continued muscular traction is accompanied by rotation in a cranioventral direction toward or into the sublumbar fossa (Pilsworth 2003). Narrowing of the space between the last rib and tuber coxa often is a useful guide (Fig 20). In such cases the affected hemipelvis often appears narrower than its intact counterpart when the horse is viewed from behind. There may also be pain on palpation of the tuber coxa and crepitus may be appreciated in the acute phase before significant haemorrhage has developed. Fractures of the ilial shaft are immediately life threatening.


While the degree of pain/lameness exhibited is not an accurate guide to the location or severity of the injury, horses with displaced fractures of the ilial shaft usually are extremely distressed. Pain in these animals often is not controlled adequately by any analgesic. Displacement of ipsilateral tuber sacrale and tuber coxa must be viewed with extreme caution as it necessitates fracture of the ilial shaft, wing shaft junction or a comminuted fracture of the ilial wing. Displaced fractures of the ilial shaft or at the junction of the shaft and


a)


b)


Iliolumbar


Internal Iliac


External Iliac


Iliacofemoral


Fig 19: Equine pelvic girdle showing the location of principal adjacent arterial trunks


Fig 20: Reduced costocoxal (sublumbar) space of a displaced fracture of the right ilial wing/tuber coxa (a) compared with its left counterpart (b).


© 2016 EVJ Ltd


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