Analytical validation of five diagnostic tests for the detection of polymorphonuclear cells in stallion semen.
Authors: Ferrer Maria Soledad, Hurley David John, Norton Natalie, Ellerbrock Robyn Elliene
Journal: Journal of equine veterinary science
Summary
# Diagnosing Inflammation in Stallion Semen: Which Test Works Best? Polymorphonuclear cells (PMNs) in ejaculates indicate reproductive tract inflammation and can compromise fertility, yet equine practitioners lack consensus on the most reliable detection method. Ferrer and colleagues systematically evaluated five diagnostic approaches—haemacytometer counting, cytology, leucocyte esterase dipstick testing (LEDT), peroxidase testing, and CD13 immunostaining—by incubating purified stallion sperm with controlled PMN concentrations ranging from zero to 10 × 10⁶ cells/ml, then measuring the motility impact after four hours at body temperature. The leucocyte esterase dipstick emerged as the clear screening choice with 100% sensitivity, though its 65% specificity means positive results require confirmation; conversely, the haemacytometer, peroxidase test, and CD13 immunostaining all achieved 95% specificity but sensitivity ranged only from 47–60%, whilst cytology managed 78% sensitivity with 95% specificity. Critically, sperm motility only declined significantly when PMN concentrations reached 5 × 10⁶ cells/ml or higher, establishing a practical clinical threshold for leucospermia diagnosis. For practical application, LEDT offers excellent value as a rapid stall-side screening tool, but clinicians should confirm any positive result with either peroxidase or CD13 testing to avoid false positives and unnecessary treatment decisions.
Read the full abstract on PubMed
Practical Takeaways
- •Use LEDT as a quick, economical screening test for PMNs in stallion semen before breeding, but always confirm positive results with a more specific test to avoid unnecessary treatment
- •Understand that even moderate PMN contamination (0.25–2.5 × 10⁶ PMN/ml) may not affect sperm motility in the short term, but concentrations ≥5 × 10⁶ PMN/ml should trigger clinical concern
- •When leukospermia is suspected, CD13 immunostaining or peroxidase testing provides better specificity than LEDT alone and should be part of the diagnostic confirmation protocol
Key Findings
- •Leucocyte esterase dipstick test (LEDT) had 100% sensitivity for detecting PMNs but only 65% specificity, requiring confirmation with peroxidase or CD13 staining
- •Hemacytometer and CD13 immunostaining detected PMN differences at the lowest concentration tested (2.5 × 10⁶ PMN/ml)
- •Sperm motility was significantly reduced only at PMN concentrations ≥5 × 10⁶ PMN/ml after 4 hours at 38°C
- •LEDT is a practical stall-side screening tool but positive results should be confirmed with peroxidase-positive or CD13-positive cell identification due to lower specificity