Interpretation of canine and feline blood smears by emergency room personnel

Background Interpretation of blood smears is commonly used to provide rapid laboratory evaluation of animals in veterinary emergency practice, but the accuracy of results of blood smear interpretation by emergency room personnel (ERP) compared with evaluation by trained veterinary clinical pathology personnel is unknown. Objective The goal of this study was to compare blood smear evaluation by ERP with that of clinical pathology personnel. Methods All animals that had a CBC determined by a diagnostic laboratory and had blood smears evaluated by personnel at the Foster Hospital for Small Animals Emergency Room between September 2008 and July 2009 were eligible for study inclusion. ERP who evaluated blood smears completed standardized forms with estimates of the WBC and platelet counts and evaluation of RBC and WBC morphology. Results from point-of-care assessment were compared with automated or manual results reported by the veterinary diagnostic laboratory. Results One hundred and fifty-five blood smears were evaluated. There was moderate agreement (kappa value, 0.63; 95% confidence interval [CI]: 0.52, 0.74) between estimated platelet counts by ERP and automated counts. Poor agreement was found between estimated WBC counts by ERP and automated counts (kappa value, 0.48; 95% CI: 0.37, 0.60). Specific abnormalities with a high likelihood of clinical significance, eg, toxic change, nucleated RBCs, spherocytes, hemoparasites, and lymphoblasts, were not predictably identified by ERP. Conclusions ERP interpretation of canine and feline blood smears should be used cautiously and should not replace evaluation by a veterinary diagnostic laboratory.