Antimicrobial Resistant Bacteria in Cooled Stallion Semen and Post-Insemination Uterine Lavage Fluid Antibiotic addition to cooled semen extenders is standard practice for bacterial control during storage, yet this may contribute to antimicrobial resistance development and introduce resistant organisms into the mare’s uterus at insemination. This study screened commercial cooled semen and post-insemination uterine lavage fluid for the presence… Read More: Antimicrobial Resistant Bacteria in Cooled Stallion Semen »
Cryptorchidism in the colt – This article describes the different forms, tests, resolutions and outcomes of cryptorchidism seen in the male horse (colt or stallion). by Jos Mottershead What is Cryptorchidism in the Colt? Before birth, the colt’s testes are located within the abdominal cavity. Testicular descent normally occurs during late gestation or shortly after birth1. Sometimes for… Read More: Cryptorchidism in the Colt »
Semen Assessment as a Fertility Predictor in Stallions Accurate stallion semen assessment as a fertility predictor need not rely on expensive equipment. This study investigated whether basic light microscopy assessments of sperm motility, membrane integrity, and morphology could reliably distinguish fertile from sub-fertile stallions under field conditions. Study Design: 24 frozen semen batches from 24 Arabian and Straight… Read More: Semen Assessment as a Fertility Predictor »
Post-Thaw Sperm Motility Comparing Automated Freezer vs. Styrofoam Box Across Multiple Cryoprotectants Standardizing equine semen cryopreservation is challenging due to variability in freezing equipment and cryoprotectant selection. This study compared a computer-controlled automated freezing machine vs. Styrofoam box method across four cryoprotectant combinations to assess post-thaw sperm motility outcomes. Study Design: 4 stallions (ages 4–20); 4 semen collections… Read More: Automated Freezing Machine vs. Styrofoam Box »
Prostanoids as Markers of Oxidative Stress in Stallion Semen Standard pre-processing semen assessment does not reliably predict quality after chilled storage. Oxidative stress in stallion semen during cooling damages sperm membranes via lipid peroxidation, reducing fertilizing potential. This study investigated whether seminal plasma prostanoids — established lipid peroxidation biomarkers — could predict chilled semen quality in stallions. Study… Read More: Prostanoids as Markers of Oxidative Stress in Stallion Semen »
Pre-Freeze Centrifugation Extenders Selection for Optimizing Equine Semen Cryopreservation Cryopreservation exposes spermatozoa to significant physical and chemical stress, making pre-freeze semen centrifugation extender selection critical for maintaining sperm viability and membrane integrity. This study compared four extender formulations — with and without cholesterol and pentoxifylline — to identify the most effective option for pre-centrifugation use in equine semen… Read More: Pre-Freeze Semen Centrifugation Extenders »
Protective Effect of Semen Extenders on Pre-Freeze Shipped Semen During Refrigeration at 5°C for 24 Hours Refrigerating stallion semen at 5°C for 24 hour shipment prior to freezing offers a practical field-based alternative when on-site cryopreservation is not feasible. This study evaluated the effect of semen extenders on pre-freeze shipped semen in four commercial diluents used within a… Read More: Effect of Semen Extenders on Pre-Freeze Shipped Semen »
Stallion Dismount Latency and Pregnancy Outcomes in Thoroughbred Horses In Thoroughbred natural service breeding, dismount semen — residual urethral semen collected after copulation — is routinely used as a proxy for ejaculate quality. This study investigated whether the duration a stallion remains mounted post-ejaculation (stallion dismount latency) influences both dismount sample composition and pregnancy outcomes. Study Design: 62… Read More: Stallion Dismount Latency and Pregnancy Rates »
Testicular and Epididymal Gene Expression Changes in Response to Scrotal Heating in Stallions Heat stress is a well-recognized cause of testicular and epididymal dysfunction, yet the underlying molecular events driving these changes remain poorly understood. This study used transcriptomic analysis to characterize early gene expression responses in testicular and epididymal tissues following acute scrotal insulation in stallions. Study… Read More: Changes in Response to Scrotal Heating »
Increasing Sperm Membrane Cholesterol Improves Cold Shock Resistance and Cryosurvival in Stallions Stallion sperm are inherently sensitive to cold shock due to a low cholesterol-to-phospholipid membrane ratio (0.38–0.45), compared to cold-shock-resistant species such as humans and rabbits (0.88–0.99). This study investigated how much cholesterol supplementation — delivered via cholesterol-loaded cyclodextrins — is required to protect stallion sperm from… Read More: Cholesterol Improves Cold Shock Resistance »
