Semen quality of stallions challenged with the Kentucky 84 strain of equine arteritis virus.

The research article explores how the equine arteritis virus (EAV), particularly the Kentucky 84 strain, affects the quality of semen in stallions. It concludes that the disease symptoms like fever and scrotal edema have negative impacts on semen quality, rather than the presence of the virus itself.

Study Procedure

• The researchers selected seven stallions for the study and infected them intranasally with the Kentucky 84 strain of the equine arteritis virus.
• The stallions were monitored for clinical symptoms of EVA (equine viral arteritis) for 42 days after inoculation.
• Semen samples were repeatedly collected from the horses – every second day for the first 15 days post-inoculation, and twice a week up to day 79. Further samples were collected on days 147, 149 and 151.
• The researchers then evaluated the semen samples for motion characteristics, total spermatozoa numbers, membrane integrity, and sperm morphology.
• Virus infectivity titers in the semen samples were determined using RK-13 cells.

Findings

• The study found a significant decrease in sperm quality from 9 days to 76 days post-inoculation.
• The research team fitted LOWESS (locally weighted scatterplot smoothing) curves for each stallion to quantify the spermatozoa’s exposure to fever, the virus, and edema over 67 days prior to each ejaculation.
• By employing linear mixed models, the team was able to isolate the impact of each factor on the quality of the semen.

Conclusion

• The study concluded that symptoms of the disease, such as scrotal edema and fever, have significant detrimental effects on all the parameters of semen quality.
• However, the virus itself was found to have little to no direct effect on semen quality. This was inferred because viral titers remained high even after semen quality had returned to its normal baseline.