Amplified androstenedione enzymeimmunoassay for the diagnosis of cryptorchidism in the male horse: comparison with testosterone and estrone sulphate methods.

The research outlines the validation of an Amplified Enzymeimmunoassay (EIA) for androstenedione in diagnosing cryptorchidism in male horses, by comparing its effectiveness with traditional methods like testosterone and estrone sulphate tests. The study, conducted on 115 pure Spanish and Arabian horses, proves androstenedione EIA to be a more reliable, rapid, and cost-effective alternative to other methods.

Study Design and Execution

• Researchers validated an Amplified Enzymeimmunoassay (EIA) for the hormone androstenedione, intending to use it as a diagnostic tool of equine cryptorchidism. This abnormality is common among male horses where one or both testicles fail to descend.
• The study involved 115 horses, which included 30 geldings (castrated horses), 60 bilateral cryptorchids (horses with both testicles undescended), and 25 stallions (intact male horses).
• Comparative analysis was conducted between androstenedione EIA and previously used diagnostic methods—measurement of testosterone and estrone sulphate concentrations.

Results and Findings

• The detection limit for the Androstenedione EIA was low at 1.54 pg/ml and the standard curve for the hormone ranged from 0 to 1 ng per well. The reliability of the assay was demonstrated by the low intra- and inter-assay coefficients of variation (under 8.2% and 9.3% respectively).
• Recovery rate of known androstenedione concentrations averaged from 96.62% to 97.63%.
• Significant differences were found in androstenedione serum concentrations across the horse groups: Stallions showed highest concentration (10.52 ng/ml), followed by cryptorchids (0.51 ng/ml), and geldings (0.03 ng/ml).

Diagnostic Validation Parameters

• Estrone sulphate had a lower positive predictive value (0.85), higher number of false positives, and lower specificity (0.84).
• Testosterone exhibited a high number of false negatives and a negative predictive value of 0.85, indicating lower sensitivity (0.85).
• Among the three hormones, androstenedione emerged as the most reliable indicator for equine cryptorchidism with fewer horses diagnosed as false positives (0.93) or negatives (0.91). This technique yielded higher sensitivity, specificity, and efficiency than the other two methods.

Conclusion

• The Amplified Enzymeimmunoassay for androstenedione proved to be an effective, rapid, and affordable alternative to the traditional methods. It demonstrated high sensitivity and specificity in diagnosing cryptorchidism in male horses.