The adverse effects of testicular hyperthermia on semen quality in stallions are attenuated by oral pentoxifylline treatment

BACKGROUND: Testicular hyperthermia impairs spermatogenesis and semen quality in stallions, but pharmacological strategies to improve recovery after testicular injury remain limited. AIMS/OBJECTIVES: This study evaluated whether oral pentoxifylline improves recovery of semen quality after experimentally induced scrotal heat stress in stallions. METHODS: Fourteen healthy stallions were allocated to three groups: control (CRL; n = 4), testicular degeneration induced by scrotal heat stress (DEG; n = 5), and testicular degeneration treated with pentoxifylline (DEG+PTX; n = 5). Testicular degeneration was induced by scrotal thermal insulation. Pentoxifylline was administered orally (17 mg/kg) for 30 consecutive days following heat stress. Semen was collected over a 60-day period and evaluated for sperm kinematics, morphology, plasma membrane integrity, oxidative stress markers and apoptotic activity. Data were analyzed using mixed models or non-parametric tests, as appropriate, with statistical significance set at P < 0.05. RESULTS: Scrotal heat stress resulted in reduced sperm motility, plasma membrane integrity and sperm concentration, alongside increased sperm defects, lipid peroxidation and activation of apoptotic pathways. Pentoxifylline treatment improved total and progressive sperm motility and accelerated recovery of plasma membrane integrity, reaching values comparable to controls earlier than untreated stallions. In addition, pentoxifylline reduced lipid peroxidation, sperm morphological abnormalities and caspase-3/7 activation. CONCLUSION: In conclusion, oral pentoxifylline attenuates heat-induced spermatogenic dysfunction in stallions by reducing oxidative stress and apoptosis, supporting its potential as a pharmacological strategy to enhance recovery of semen quality following testicular injury.