Evaluation of the utility and accuracy of body fluids containing red blood cells to determine canine and feline blood types

OBJECTIVE: To examine the accuracy of using body fluids macroscopically suspected to contain erythrocytes to determine the blood type in dogs and cats by use of an immunochromatographic cartridge (ICC), compared to systemic blood as the reference standard. DESIGN: Prospective study. SETTING: University teaching hospital. ANIMALS: Thirty client‐owned dogs and 8 cats. INTERVENTIONS: Dogs and cats with a sanguineous or serosanguineous body fluid (SBF) that also required a blood sample were eligible for inclusion. PCV and blood type were determined in all blood and fluid samples. For body fluids with a low PCV and discordant blood type results compared to systemic blood, sample concentration and repeat blood typing from the fluid was performed when enough sample was available. MEASUREMENT AND MAIN RESULTS: Body fluid samples consisted of 16 pleural (11 dogs; 5 cats), 12 peritoneal (10 dogs; 2 cats), and 4 canine pericardial effusions, 3 urine samples, and 1 each of feces and epistaxis from dogs and a seroma sample from a cat. Median (range) manual PCV of blood and fluid samples was 34% (14%–66%) and 6% (0.5%–70%) for dogs and 28% (14%–48%) and 14% (0.5%–19%) for cats, respectively. Dogs were correctly classified as being DEA 1 negative, DEA 1 positive, and DEA 1 weak positive when using body fluid for blood typing 13 of 14, 4 of 9, and 5 of 7, respectively. All reference blood type to fluid blood type (FBT) discordant results had a body fluid PCV equal to or below 2%. Subsequently concentrated body fluid samples had a PCV above 8% and repeat FBT matched reference blood type (RBT). All cats were classified as type A by all RBTs and FBTs. CONCLUSIONS: Body fluids containing erythrocytes may be utilized to blood type dogs if sufficiently concentrated and type A cats.