Background: Serum amyloid A (SAA) is a major acute phase protein in horses which could be a useful tool for assessing clinical response to treatment of bacterial pneumonia in adult horses.
Objectives: To monitor SAA concentration in response to treatment and identify associations among SAA concentration, WBC and neutrophil counts, and fibrinogen in bacterial pneumonia in adult horses.
Animals: Eighteen adult horses with bacterial pneumonia.
Methods: Prospective clinical study. Horses hospitalized with bacterial pneumonia were enrolled and SAA concentration and vital signs were assessed daily. SAA concentration was measured by a handheld meter. CBC and plasma fibrinogen were assessed on days 0, 1, and 2, then every 3 days until discharge. Data were not normally distributed and therefore were log transformed. Log-transformed data were analyzed and comparisons were performed on LSMeans by the 2-sided Student's t-test at the 5% level of significance.
Results: Geometric mean SAA concentration on day 0 was 537 μg/mL (SE 383 μg/mL). Geometric mean SAA concentration decreased significantly over time (P = .0001), peaking at day 2 (geomean 1038 μg/mL, SE 261.7 μg/mL) and decreasing until discharge. Plasma concentration of fibrinogen (P = .06), neutrophil count (P = .48), and WBC count (P = .07) did not change significantly over time.
Conclusions and clinical importance: SAA concentration decreased significantly over the course of treatment and correlated with clinical improvement of pneumonia whereas fibrinogen, neutrophil, and WBC counts did not.
Keywords: acute phase; antimicrobials; equine; microbiology; pleuropneumonia; respiratory.
© 2023 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.