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Conference abstract, 2012

Decrease in Advia 2120 MPXI and a Monocyte Identification Error Occur late After Endotoxin Treatment of Horses

Tvedten, Harold; Lilliehöök, Inger; Nostell, Katarina; Edner, Anna; Bröjer, Johan

Abstract

Decreased myeloperoxidase index (MPXI) determined by the Advia 2120 hematology system has been suggested as a diagnostic aid in horses with systemic inflammation. However MPXI was not reported to be helpful in septic and neutropenic foals. We analyzed MPXI and other Advia automated results in 8 horses treated with an infusion of endotoxin solution (Sigma-Aldrich, St.Louis, USA) intravenously over 6 hours. The total dose per horse was 500 ng/kg body weight. Blood was analyzed with an Advia 2120 every hour for the first 10 hours, every 6 hours until 78 hours and then at 150 hours after infusion. A prominent decrease in MPXI was not noted until 66 hours after infusion with a maximum decrease at 150 hours after infusion. MPXI in that horse was 5.9 to 7.4 prior to infusion and was lowest (-22.7) at 150 hours. The decreased peroxidase staining of neutrophils caused also an increase in neutrophils incorrectly classified as monocytes. The percentage of cells misclassified as monocytes by Advia was determined by dividing the error (automated minus manual % monocytes) by total number of neutrophils. The monocyte error in that horse peaked at 89 % at 150 hours. The monocyte error and decreased MPXI were seen quite late after infusion of endotoxin. The late appearance of these changes in neutrophils may explain why changes in peroxidase staining of neutrophils were not seen in septic foals and inconsistently in adult horses if their hematologic evaluation was performed too early after onset of infection.

Published in

Veterinary Clinical Pathology
2012, Volume: 41, number: 4, pages: 11
Publisher: American College of Veterinary Pathology
DOI: 10.1111/j.1939-165X.2012.00471.x

Conference

American Society for Veterinary Clinical Pathology (ASVCP) 47th Annual Meeting In conjunction with the American College of Veterinary Pathologists (ACVP) 63rdAnnual Meeting