Rhodococcus equi pneumonia in foals: an assessment of the early diagnostic value of serum amyloid A and plasma fibrinogen concentrations in equine clinical practice.
Authors: Passamonti F, Vardi D M, Stefanetti V, Marenzoni M L, Prato S, Cévese P, Coletti M, Pepe M, Casagrande Proietti P, Olea-Popelka F
Journal: Veterinary journal (London, England : 1997)
Summary
# Editorial Summary: Early Diagnosis of Rhodococcus equi Pneumonia in Foals Rhodococcus equi pneumonia remains a significant challenge in foal health management, with early detection critical for improving outcomes before clinical signs become apparent. Passamonti and colleagues evaluated whether weekly monitoring of two readily available blood markers—serum amyloid A (SAA) and plasma fibrinogen—could identify infected foals earlier than standard thoracic ultrasonography, testing these alongside conventional diagnostic protocols in a prospective clinical setting. SAA proved unreliable as a weekly screening tool for subclinical infection, though the marker did provide useful real-time information about disease progression and treatment response once clinical signs developed. Plasma fibrinogen concentrations showed more promise as a potential screening parameter when measured from one week of age onwards, with serial weekly testing potentially identifying at-risk foals before ultrasonographic evidence of pyogranulomas becomes apparent. Whilst these findings suggest fibrinogen warrants further investigation as a practical screening biomarker, practitioners should note that establishing robust reference intervals and understanding fibrinogen kinetics in affected foals will be essential before implementing this approach clinically, and ultrasonography remains the current gold standard for diagnostic confirmation.
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Practical Takeaways
- •Weekly SAA testing alone is not recommended as an early screening tool before clinical signs appear; reserve SAA testing for monitoring treatment response once pneumonia is confirmed
- •Consider implementing weekly plasma fibrinogen monitoring from 1 week of age as a potential cost-effective screening protocol, pending establishment of age-appropriate reference intervals
- •Continue relying on thoracic ultrasonography as the primary early diagnostic method until fibrinogen reference intervals are established and validated in practice
Key Findings
- •Serum amyloid A (SAA) tested weekly does not reliably detect R. equi pneumonia before clinical signs appear
- •SAA concentrations can provide real-time information about infection progression and treatment effectiveness once clinical signs are present
- •Weekly plasma fibrinogen monitoring starting at 1 week of age shows promise as a potential screening test for identifying foals suspected of R. equi infection
- •Thoracic ultrasonography with abscess scoring remains the parallel diagnostic standard for early detection