Use of thermography in the long-term evaluation of scrotal surface temperature and its impact on seminal quality in stallions.

Scrotal surface thermography is a non-invasive method for assessing testicular thermoregulation in stallions; however, few studies have explored the application of this technique concerning the thermal physiology of equine reproductive systems. This study aimed to evaluate the consistency of testicular thermoregulation in stallions over a year using thermography to measure the scrotal surface temperature (SST). Moreover, we assessed the best region for measuring the surface body temperature compared with the SST. Ten light-breed stallions were used in the experiment. Thermographic images of the scrotal and body surfaces (neck and abdomen) were captured. Fresh, cooled and frozen-thawed semen samples were evaluated to verify the impact of thermoregulation on semen quality. Testicular thermoregulation was maintained throughout the year in stallions amidst changes in the external temperature, as evidenced by the weak correlation between the SST and ambient temperature. A lower correlation was observed between the environmental temperature and body surface temperature (BTS) obtained from the abdomen (BTS-A; R = .4772; p < .0001) than with that obtained from the neck (BTS-N; R = .7259; p < .0001). Moreover, both BTS-A and SST were simultaneously captured in a single image. The consistent quality of the fresh, cooled and frozen semen suggests efficient thermoregulation in stallions throughout the year.