Emerging Non-Invasive Imaging Tools for Andrological Assessment in Male Reproduction: The Role of Infrared Thermography and Color Doppler Ultrasonography.

Male fertility assessment is crucial to reproductive management in livestock and companion animals. Traditional breeding soundness evaluations (BSE), which include semen analysis and reproductive tract examination, sometimes fail to detect reproductive dysfunction in its early stages. Advancements in Infrared Thermography (IRT) and Color Doppler Ultrasonography (CDU) have provided non-invasive, real-time, and objective tools to evaluate testicular function, thermoregulation, and blood flow dynamics. CDU enables the quantification of testicular blood perfusion (TBP) through Doppler indices such as Resistive Index (RI) and Pulsatility Index (PI), which are sensitive indicators of testicular function. Meanwhile, IRT assesses scrotal temperature gradients, which are critical for spermatogenesis and semen quality. The standardization of diagnostic thresholds and their cross-species applicability continue to be unsolved issues despite their increasing clinical significance. Additionally, male fertility is seriously threatened by climate change and heat stress, which calls for additional research on IRT and CDU in thermoregulatory responses. The widespread use of these technologies can increase reproductive success in companion and agricultural animals, decrease financial costs associated with subfertility, and improve breeding efficiency. This review comprehensively analyses these imaging modalities, compares their advantages and limitations, and explores their integration into routine andrological assessments.