Objective: To determine history; clinical, radiographic, ultrasonographic, and scintigraphic features; management; and outcome associated with third trochanter fractures in horses.
Design: Retrospective case series.
Animals: 8 horses.
Procedures: Records from 2000 to 2012 were reviewed, and signalment, case history, severity and duration of lameness, results of physical and lameness examinations, imaging findings, management, and outcome were evaluated.
Results: All horses had a history of acute onset of severe lameness. Four of the 8 horses had localizing physical signs of fracture. No specific gait characteristics were identified. Ultrasonographically, there was a single bony fragment displaced cranially in 7 of 8 horses and multiple bony fragments in 1. Concurrent gluteus superficialis muscle enthesopathy was identified in 7 horses. A standing craniolateral-caudomedial 25° oblique radiographic view was obtained in 3 horses to document the lesion and revealed in all 3 horses a simple complete longitudinal fracture between the midlevel and the base of the third trochanter. Nuclear scintigraphy was used to identify the affected area of the limb for further examination in 2 horses. Follow-up revealed that fractures healed with a fibrous union, with persistence of cranial displacement of the fragment. Lameness resolved after nonsurgical management for all horses.
Conclusions and clinical relevance: Fracture of the third trochanter should be considered as a cause of hind limb lameness in horses when the proximal portion of the limb is affected. Diagnosis can easily be made with ultrasonography, but nuclear scintigraphy may help in identifying the lesion. Prognosis for return to athletic activity is good after an appropriate period of rest and restricted exercise.