Utility of serum amyloid A in monitoring clinical response to antimicrobial treatment in horses with bacterial pneumonia.
Authors: Hepworth-Warren Kate L, Estell Krista, Cowles Bobby, Amodie Deborah, Crisman Mark
Journal: Journal of veterinary internal medicine
Summary
Serum amyloid A (SAA), a major acute phase protein in horses, may offer clinicians a more responsive biomarker than traditional haematological parameters for tracking treatment efficacy in bacterial pneumonia. Researchers monitored 18 hospitalised adult horses with bacterial pneumonia, measuring SAA concentration daily via handheld meter alongside complete blood counts and plasma fibrinogen on days 0, 1, 2, and thereafter every three days until discharge. SAA concentrations demonstrated a distinctive pattern: beginning at a geometric mean of 537 µg/mL on day 0, peaking at day 2 (1038 µg/mL), then declining significantly throughout the treatment course (P = 0.0001), mirroring clinical improvement—whereas fibrinogen, neutrophil counts, and total WBC counts showed no significant temporal changes. Unlike conventional inflammatory markers, SAA's rapid response to antimicrobial therapy and clear correlation with clinical recovery suggests it could serve as a sensitive prognostic tool for assessing treatment response and informing decisions about hospitalisation duration or therapeutic adjustments. For practitioners, incorporating SAA measurement into pneumonia monitoring protocols may provide objective evidence of response earlier than clinical assessment alone, though the relatively small cohort warrants validation in larger populations before widespread adoption.
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Practical Takeaways
- •SAA measured by handheld meter provides a practical, objective biomarker for monitoring treatment response in horses with bacterial pneumonia, potentially superior to traditional markers like WBC and fibrinogen
- •Expect SAA levels to peak around day 2 of treatment before declining; serial measurements can help clinicians assess whether a horse is responding appropriately to antimicrobial therapy
- •SAA may help differentiate genuine clinical improvement from other causes of persistent clinical signs, supporting clinical decision-making regarding treatment duration or modifications
Key Findings
- •Serum amyloid A (SAA) concentration decreased significantly over the course of antimicrobial treatment (P = 0.0001), peaking at day 2 (geometric mean 1038 μg/mL) before declining until discharge
- •SAA concentration correlated with clinical improvement of pneumonia in adult horses
- •Plasma fibrinogen, neutrophil count, and WBC count did not change significantly over time and did not correlate with clinical response to treatment