Canine semen evaluation using a new configuration of the CASA system

For many years, the computer-assisted sperm analysis (CASA) has been one standard in the laboratory for semen evaluation, with no clear description of a species-specific setup.

This study aimed to adjust the cell detection parameters (Head Brightness Minimum "HBM" and Head Size Minimum "AREA") of the CASA system and to assess their effects on evaluating canine semen, specifically concentration and motility.

For this purpose, 20 ejaculates were collected from six dogs and subjected to microscopic assessment of motility, concentration evaluation using the SDM1 photometer, cell counting using a Neubauer chamber, and kinetic and morphometric analysis using the HT-IVOS II CASA system. Each CASA analysis was recorded, and then the video was re-analyzed by changing the two cell detection parameters (HBM and AREA). A total of 27 settings were used, and 560 CASA assessments were performed. Data were statistically analyzed using IBM SPSS.

The results showed that the HT-IVOS II CASA system provided an average concentration value (287.17 million spermatozoa (SPZ)/ml) much closer to that obtained by the reference method, Neubauer counting (286.45 million SPZ/ml), compared to the photometer (260.35 million SPZ/ml), which deviated from the gold standard technique by 26 million. In contrast, the IVOS with the adjusted setting (HBM140, AREA4) only presented a difference of 0.5. The IVOS II with the adjusted showing a strong correlation with the Neubauer count and the SDM photometer, with a correlation coefficient of R= 0.94. A perfect concordance was recorded between total and progressive motility evaluated by conventional microscopy and the percentages of motile and progressive sperm analyzed by HT-IVOS at values 120 and 140 for the HBM and 4 and 6 μm² for the AREA.

An optimal cell detection parameter setting (HBM: 140 and AREA: 4 μm²) was selected and proposed for the HT-IVOS II CASA system.