Comparison of Westergren and Automated Erythrocyte Sedimentation Rate Measurements in Dogs and Cats

The erythrocyte sedimentation rate (ESR) is a routine marker of inflammation in human medicine, and it is influenced by erythrocyte features and the level of some plasma proteins. The Westergren method is the reference technique in humans; however, this manual technique has been scarcely used in animals and has not been validated. An automated veterinary in-clinic device (MINI-PET) is able to measure ESR on EDTA-blood tubes. This study aimed to evaluate the comparability of ESR values measured with two tests in cats and dogs admitted to a veterinary clinic and in anemic individuals. Analytical comparability and decision limits were calculated in both species and clinical groups. Comparisons were also made between the two species. The two ESR methods had different decision limits in the investigated population of dogs and cats, and a method-specific interpretation of their results is suggested. Healthy cats had significantly higher values than healthy dogs using both the Westergren and MINI-PET methods. By both methods, anemic individuals had higher ESR values than the matched subgroups with erythrogram values within the reference range, probably due to concurrent inflammation in most anemic animals studied. In general, ESR measures should be evaluated in conjunction with erythrogram values.