The inability of spectral Doppler ultrasonography to identify stallions with testicular dysfunction.
Authors: Pozor Malgorzata A, Macpherson Margo L, Kelleman Audrey A, Smith Hannah, McNaughten Justin W
Journal: Journal of equine veterinary science
Summary
# Editorial Summary Spectral Doppler ultrasonography has been proposed as a diagnostic tool for identifying testicular dysfunction in stallions, yet Pozor and colleagues' 2025 retrospective analysis reveals significant limitations in its clinical utility. The researchers tracked a pony stallion over four years as it experienced age-related testicular degeneration, documenting dramatic reductions in testicular volume and progression to azoospermia, whilst most spectral Doppler parameters remained unchanged; they then compared Doppler findings from four younger horses with testicular dysfunction against five fertile controls, finding that total arterial blood flow (TABF) was the only parameter showing group-level differences (P < 0.005), though individual values overlapped substantially between dysfunctional and fertile stallions. These overlapping measurements in individual cases underscore the fundamental problem: whilst Doppler parameters may show statistical significance at the population level, they cannot reliably distinguish affected stallions from normal ones in practice. For practitioners relying on ultrasonographic assessment to identify breeding soundness problems, this work signals that spectral Doppler alone should not be used as a standalone diagnostic; instead, testicular dysfunction diagnosis must continue to depend on conventional B-mode ultrasound dimensions, thorough semen analysis and clinical evaluation, with Doppler serving at best as a supplementary rather than definitive tool.
Read the full abstract on PubMed
Practical Takeaways
- •Do not rely on spectral Doppler ultrasonography as a standalone diagnostic tool for testicular dysfunction in stallions; semen analysis and testicular dimensions remain more reliable indicators
- •When TABF values overlap between normal and affected stallions, the test has limited clinical utility for individual animal assessment despite group-level statistical differences
- •Combine Doppler findings with direct testicular measurement, semen parameters, and clinical examination for comprehensive reproductive assessment in stallions
Key Findings
- •Spectral Doppler ultrasonography failed to detect testicular dysfunction in most cases despite dramatic decreases in testicular volume and loss of sperm production
- •Total Arterial Blood Flow (TABF) rate was the only Doppler parameter that differed between fertile and dysfunctional stallions (P < 0.005), but values overlapped between groups when individual stallions were analyzed
- •TABF rate increased in a degenerating testis primarily due to decreased testicular volume rather than true hemodynamic changes
- •Spectral Doppler ultrasonography is not a reliable diagnostic method for identifying testicular dysfunction in stallions on an individual basis