Multiple Myeloma

Multiple myeloma is a condition in which a type of white blood cell called a plasma cell begins to multiply abnormally in the bone marrow. These cells can crowd out healthy blood cells and produce abnormal proteins that circulate in the blood and may be filtered into the urine. The condition tends to affect older dogs more commonly than cats, and it develops gradually. Owners often notice signs that can seem unrelated at first—lethargy, weakness, increased thirst, or lameness that may come and go. Some dogs develop nosebleeds or bruise more easily. In other cases, the condition is detected through routine blood work before any outward signs appear. The variety of possible presentations reflects the different ways these abnormal cells and their proteins can affect the body. This page explores what signs may prompt investigation, the mechanisms by which plasma cells behave this way, how the condition is identified through blood tests and imaging, and the range of approaches that exist to manage it. The course and outlook vary considerably between individuals.