Distinguishing feline IBD from small cell lymphoma requires intestinal biopsy, with the distinction having major welfare and treatment implications since lymphoma typically responds to chemotherapy while IBD requires immunosuppression.
The IBD-versus-lymphoma diagnostic challenge has profound welfare implications. Cats treated empirically for IBD who have undiagnosed lymphoma miss the opportunity for specific therapy that typically produces 2+ years of good quality life. The diagnostic procedure (endoscopic or surgical biopsy) carries anesthetic risk and some cost, but the welfare benefit of accurate diagnosis - appropriate treatment selection and realistic prognosis - justifies the investment for most cats with significant clinical signs. Welfare-centered diagnostic planning for cats with refractory or progressive GI signs includes histopathological biopsy as the standard of care, not an optional advanced investigation.