Alteration of semen quality in dogs after creation of varicocele

A left vein varicocele was created in male dogs by partially obstructing the left renal vein medial to the entrance of the left internal spermatic vein. Eight dogs had semen parameters determined preoperatively (2 times/week for five weeks) and postoperatively (2 times/week for twelve weeks). Semen quality was altered by the experimental varicocele. A significant decrease in sperm count, motility, per cent viable, and per cent oval sperm were noted. Semen volume was not affected. The possible chemical influence of serotonin is mentioned. Testosterone levels were unchanged by the varicocele. Histologic findings in the left and right testicles are mentioned before and after creation of the varicocele.