Immune-mediated haemolytic anaemia occurs less commonly in cats than dogs. Young to middle-aged cats appear most commonly affected. In addition, it may be more difficult to diagnose for several reasons: jaundice is less commonly seen on clinical examination; spherocytosis is not reliable in cats, as their normal red blood cells are smaller and lack central pallor; cats are more prone to haemolysis from oxidative damage due to e.g. drugs or toxins (methimazole, paracetamol, garlic, onions), Heinz Body anaemia (diabetes mellitus) enzymopathies (pyruvate kinase deficiency); cat erythrocytes commonly form rouleaux, which can be misinterpreted as agglutination; IMHA may be non-regenerative, decreasing the index of suspicion of IMHA as the cause of anaemia. As with canine disease, primary IMHA must be differentiated from secondary IMHA. Recognised causes of secondary IMHA include infections (e.g. M. haemofelis, Feline Coronavirus, retrovirus infection, Babesia), inflammatory disease processes (e.g. pancreatitis, cholangiohepatitis) and drugs (e.g. propylthiouracil). There is no evidence that vaccination can act as a trigger for IMHA in cats, and the evidence for neoplasia acting as a trigger appears weak. Prednisolone forms the mainstay of therapy, with additional immunosuppressive drugs such as ciclosporin, chlorambucil and mycophenolate mofetil also having been used in conjunction with prednisolone.