Are serum amyloid A or D-lactate useful to diagnose synovial contamination or sepsis in horses?
Authors: Robinson Claire S, Singer Ellen R, Piviani Martina, Rubio-Martinez Luis M
Journal: The Veterinary record
Summary
# Editorial Summary Prompt diagnosis of synovial sepsis in horses is critical for survival and functional recovery, yet distinguishing true infection from sterile synovial pathology remains diagnostically challenging. Robinson and colleagues evaluated whether serum amyloid A (SAA) and D-lactate measured in both blood and synovial fluid could reliably identify septic versus non-septic joint disease across 112 horses: 38 with confirmed synovial contamination or sepsis, 66 with non-septic intra-synovial conditions, and 8 healthy controls. Blood SAA demonstrated 82.4% sensitivity and 88.9% specificity (cut-off 60.7 µg/ml) for detecting synovial sepsis, whilst synovial fluid SAA showed 80% sensitivity and 73% specificity (cut-off 1.14 µg/ml), with both markers significantly elevated in septic cases compared to non-septic pathology and controls; conversely, D-lactate concentrations proved unhelpful across both fluids. For practitioners, these findings suggest that SAA—particularly blood SAA—can serve as a useful adjunctive diagnostic tool to support clinical decision-making when synovial sepsis is suspected, though it should be interpreted alongside traditional markers (cell counts, neutrophil percentage, protein concentration) and clinical presentation rather than as a standalone diagnostic criterion.
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Practical Takeaways
- •SAA measurement in both blood and synovial fluid can help distinguish septic from non-septic joint disease in horses, supporting clinical decision-making for prompt treatment of synovial sepsis
- •Blood SAA offers slightly better diagnostic accuracy (88.9% specificity) than synovial fluid SAA (73% specificity) and may be more practical to obtain in field settings
- •D-lactate should not be relied upon as a diagnostic marker for equine synovial sepsis based on current evidence
Key Findings
- •Blood and synovial fluid SAA were significantly elevated in horses with synovial sepsis compared to non-septic intra-synovial pathology and controls
- •Blood SAA demonstrated 82.4% sensitivity and 88.9% specificity for diagnosing synovial sepsis at a cut-off of 60.7 µg/ml
- •Synovial fluid SAA showed 80% sensitivity and 73% specificity at a cut-off of 1.14 µg/ml for synovial sepsis diagnosis
- •D-lactate concentrations in blood and synovial fluid were not significantly different between groups and were not useful diagnostic markers