Rib fracture as a cause of hindlimb lameness in a horse

A 2-year-old racing Thoroughbred gelding in training was presented with moderate (6/10) right hindlimb lameness unresponsive to regional anaesthesia of the right hindlimb. Gamma scintigraphic examination revealed severe, focal, increased radio-pharmaceutical uptake over the dorsal aspect of the right 18th rib, which had an abnormal contour. Ultrasonographic examination of this area confirmed the presence of a complete, displaced fracture of the proximal aspect of the right 18th rib. Local infiltration with anaesthetic solution around the right 18th right rib (10 mL cranial and 10 mL caudal to the fracture site) abolished the right hindlimb lameness. A diagnosis of rib fracture causing moderate ipsilateral hindlimb lameness was made. The horse returned to walking exercise after 12 weeks of rest and was reported to be sound on the same limb 12 months after presentation. Caudal rib fractures should be considered as a possible cause of hindlimb lameness. Local diagnostic anaesthesia around the fracture site can aid localisation of the origin of lameness.