Correlating clinical activity and histopathologic assessment of gastrointestinal lesion severity: current challenges.

There has been increasing awareness that the severity of histopathologic lesions does not always correlate with the severity of clinical signs. Several grading systems for gastrointestinal histopathologic lesions have been generated, but there has been no widespread acceptance of one system. The World Small Animal Veterinary Association sponsored a gastrointestinal study group that produced a template of histologic changes in the gastrointestinal tract of the feline and canine in an attempt to generate widespread acceptance of a grading system. This article outlines the progress, pitfalls, and challenges in correlating histopathologic changes in the gastrointestinal tract with clinical activity.