Pattern of Coombs’ test reactivity has diagnostic significance in dogs with immune‐mediated haemolytic anaemia

Abstract

To investigate the clinical significance of the pattern of Coombs' test reactivity in dogs with immune-mediated haemolytic anaemia. Sixty-five anaemic dogs with a positive Coombs' test were included. Coombs' testing was performed at 4 and 37 degrees C with polyvalent canine Coombs' reagent and antisera specific for each of canine immunoglobulin G, immunoglobulin M and complement factor C3. The impact of performing testing with only polyvalent antiserum at 37 degrees C was assessed. Chi-squared tests were used to compare Coombs' test reactivity in dogs with primary immune-mediated haemolytic anaemia (group A) and in dogs with concurrent/underlying disease (group B). Following Bonferroni correction, significance was set at P < or = 0.003. Eleven dogs would have been regarded as Coombs' negative had they been tested with polyvalent antiserum at 37 degrees C alone. Group A dogs were significantly more likely to be positive with polyvalent antiserum and/or anti-dog immunoglobulin G at 4 and/or 37 degrees C (P < or = 0.001) and tended to be less likely to be positive with anti-dog immunoglobulin M at 4 degrees C (P=0.040). Testing of anaemic dogs with polyvalent Coombs' reagent at 37 degrees C was less sensitive than testing with monovalent reagents at 4 and 37 degrees C. The pattern of Coombs' test reactivity differed significantly between dogs with primary immune-mediated haemolytic anaemia and those with concurrent/underlying disease.