Renal Lymphoma in Cats

Renal lymphoma in cats refers to lymphoma—a cancer of lymphocytes, a type of white blood cell—that has developed in or spread to the kidneys. Lymphoma can arise in many parts of the body, and when it involves the kidneys, it may affect one or both sides, interfering with the organ's ability to filter waste and regulate fluid balance. This form is more commonly seen in older cats, though it can occur at any age. Owners often notice signs that overlap with other kidney conditions: increased thirst and urination, reduced appetite, weight loss, or quiet lethargy. In some cases, a cat may vomit occasionally or seem less interested in food over a period of weeks. Because these signs are not specific to lymphoma, the condition is typically identified through a combination of blood tests, imaging, and sometimes tissue sampling. This page explores the signals that may prompt investigation, the biological processes underlying renal lymphoma, the tests used to clarify what is happening, and the range of approaches that exist once a picture has formed. The goal is to help you understand what renal lymphoma may look like and how it is considered in the context of your cat's overall health.