Small cell (low-grade) gastrointestinal lymphoma is the most common cancer in cats and the most common form of feline lymphoma. It arises from lymphocytes — most often T-cells — that normally reside in the lining of the intestinal wall. These malignant lymphocytes accumulate gradually, disrupting the intestine's ability to absorb nutrients properly. Affected cats typically show chronic, slowly progressive signs such as weight loss, intermittent vomiting, decreased appetite, or diarrhoea. Because these symptoms closely mimic inflammatory bowel disease (IBD), and because distinguishing the two conditions can require full-thickness intestinal biopsies, diagnosis can be challenging. The good news is that small cell GI lymphoma generally responds well to oral chemotherapy (chlorambucil and prednisolone), with many cats achieving remission for one to three years or longer and maintaining an excellent quality of life throughout treatment.