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Pelvic fractures can occur as a result of a traumatic incident such as a kick or a fall, or as a result of repetitive loading during exercise (when they are most commonly incomplete “stress” fractures) (15) (33). If pelvic stress fractures are not detected, they can lead to complete fractures of the pelvis, which unfortunately are frequently fatal.
Pelvic fractures are primarily a problem of racehorses (15) and occur in both flat (15) (44) and national hunt horses (13). Stress fractures affecting the pelvis are a common cause of hindlimb lameness and poor performance but can be difficult to detect in the early stages.
Pelvic stress fractures can be progressive (135) and early detection can help prevent progression to fatal fractures.
Bones that are subjected to excessive repetitive loading, with insufficient time (rest) to adapt and remodel are susceptible to stress fracture formation.
Cyclic loading during locomotion (movement) results in bone fatigue at sites of high load, which may progress from minor micro-cracking to incomplete, non-displaced fractures. If undetected, progressive development can result in a complete, displaced fracture, which is more likely to be fatal or result in a decision to euthanase the horse (33).
Stress fractures can consist of multiple sites of fracture on one or both sides of the pelvis but the ilial wing (the largest bone within the pelvis) is a common location of pelvic stress fractures in the racehorse (135).
Likelihood of pelvic fracture occurrence has been observed to vary between trainers (15), suggesting that some training practices are associated with a higher risk of pelvic fracture than others. It may be that some training regimens do not allow for sufficient skeletal adaptation to withstand the forces placed upon it. Aspects of training that have been investigated include gallop surface type, topography and condition as well as distances worked at different speeds.
Several individual risk variables have been identified such as:
Video 1: Equine Pelvic Ultrasound Technique (UC Davis) – External and rectal scan techniques.
However, there is evidence that a significant proportion of pelvic fractures occur in training, thus, further training data would be beneficial to quantify the risk of pelvic fracture to racehorses overall.
Read more – click here to read the THN’s FULL RESEARCH REVIEW which summarises the scientific evidence available: