Scintigraphy for diagnosis of avulsions of the origin of the suspensory ligament in horses: 51 cases (1980–1993)

Abstract

Summary The medical records of 34 horses with a diagnosis of avulsion of the origin of the suspensory ligament that had been admitted to the veterinary medical teaching hospital between 1980 and 1993 were identified. In addition to clinical examination, 21 of 34 horses had scintigraphy and radiography performed during their examination. The usefulness of scintigraphy and radiography were assessed by comparing the initial findings reported in the medical record to those obtained in a retrospective review of the images. Thirty other horses with scintigraphic lesions of the proximal aspect of the third metacarpal/metatarsal bone but with a confirmed diagnosis other than avulsion of the suspensory ligament served as controls for lesion specificity. Scintigraphy (bone phase, n=21) revealed increased uptake in all horses in both reviews. Only 14 of 21 (67%) horses radiographed, however, had at least 1 lesion during the initial radiographic evaluation that was reported to be suggestive of avulsion. When the radiographs were reviewed retrospectively, the radiologist identified 18 of 21 (86%) horses with lesions consistent with avulsion. The interpretation of scintigraphy appeared to be a more repeatable and sensitive diagnostic method than radiography. However, though scintigraphy was sensitive in identifying inflammation of the proximal aspect of the metacarpal/metatarsal region, no specific diagnosis of avulsion could be made without coincident radiography; the specificity of scintigraphy in diagnosing avulsion of the suspensory ligament was only 41% (21/51). Radiography of the proximal aspect of the third metacarpal/tarsal bone was found to be falsely negative in 3 of 21 (14%) horses on retrospective evaluation and in 7 of 21 (33%) horses on initial evaluation, perhaps because radiographic signs of disease were subtle.