Objective: To investigate the associations between Coombs’ testing, haemoplasma and retroviral infections, and feline anaemia.

Methods: Haematology, Coombs’ testing (including assessment of persistent autoagglutination) and selected infection testing (haemoplasma, feline leukaemia virus/feline immunodeficiency virus provirus) were performed in blood samples collected from 60 anaemic and 60 non-anaemic cats.

Results: No association between infection and anaemia or Coombs’ positivity existed. Anaemic cats (21.7%) were significantly more likely than non-anaemic cats (0%) to have cold autoagglutination (P<0.0001), but significance (set at ≤0.0025 due to multiple testing) was not quite reached when Coombs’ positivity was compared between anaemic (40.4% and 21.7% positive at 4°C and 37°C, respectively) and non-anaemic (20% and 3.3% positive, P=0.021 and P=0.004, at 4°C and 37°C, respectively) cats. Cats with immune-mediated haemolytic anaemia were significantly more likely to have persistent cold autoagglutination (P<0.0001) and be Coombs’ positive at 37°C with polyvalent (P<0.0001), immunoglobulin (Ig)G (P<0.0001) or any antiserum (P<0.0001). Haemoplasmas and retroviruses were uncommonly detected.

Clinical Significance: Cats suspected of having immune-mediated haemolytic anaemia should be evaluated for persistent autoagglutination at 4°C as well as performing Coombs’ testing at 37°C, but positive results may occur in with other forms of anaemia. Testing for erythrocyte-bound antibodies should always be interpreted in parallel with documentation of haemolysis in anaemic cats.