LAUSR

ABSTRACT This study investigates the dose–response effects of oral melatonin on reproductive parameters in intact male Pomeranian dogs diagnosed with Alopecia X. Given melatonin's potential therapeutic effects on hair regrowth and reproductive health, this study aimed to evaluate its impact on semen quality, hormonal profiles and testicular haemodynamics. A total of 16 intact male Pomeranian dogs were randomly assigned to four groups: a control group receiving a placebo and three treatment groups receiving melatonin at low (0.1 mg/kg), medium (0.3 mg/kg) and high (0.5 mg/kg) doses, administered twice daily for 45 days. Reproductive parameters, including semen volume, sperm concentration, total sperm count, sperm motility and levels of testosterone and oestradiol 17‐ß, were assessed biweekly. Testicular haemodynamics were evaluated using pulsed Doppler ultrasonography. The results showed dose‐dependent improvements in semen quality and testicular blood flow, with the highest dose group demonstrating the most significant improvements. However, analysis of the testosterone‐to‐oestradiol ratio revealed a decrease in the treatment groups, highlighting a complex hormonal response. Although semen quality improved, the study's short duration may not have captured the full spermatogenesis cycle. These findings suggest that melatonin may enhance reproductive function in male dogs with Alopecia X, but further research is needed to clarify its long‐term endocrine effects and optimize treatment protocols.