Sensitivity and Specificity of Ultrasonographic Evaluation of Small Intestine Wall Thickness in the Diagnosis of Inflammatory Bowel Disease in Horses: a Retrospective Study

In horses, inflammatory bowel disease (IBD) usually determines a chronic wasting syndrome (CWS) which is a highly nonspecific clinical syndrome; therefore, diagnosing IBD often represents a challenge. Little is known about the accuracy of abdominal ultrasonography in horses suspected of IBD: previous studies reported abdominal ultrasonography to be useful in the diagnostic approach for IBD in the equine patient but, to the authors' knowledge, no studies assessed its accuracy. The aim of the present study was to assess sensitivity and specificity of ultrasonographic measurement of small intestine wall thickness in the diagnosis of IBD, using rectal biopsy as a reference standard. Thirty-five horses presented for CWS were retrospectively selected among a clinical population. Assessment of sensitivity, specificity, and receiving operator characteristics curve elaboration were made initially for all the patient population and then repeated including only those horses showing ultrasonographic evidence of diffuse small intestinal wall thickening. When all patients were considered, a 5.7 mm cutoff value was the best compromise between sensitivity (36.8%) and specificity (87.5%). When only those patients with diffuse thickening were considered, a 5 mm cutoff value was the best compromise between sensitivity (50%) and specificity (100%). According to the results obtained, ultrasonography appears to be a specific method for the evaluation of small intestinal wall thickness, and it could be useful in the diagnostic protocol of IBD in horses with CWS.