Valuable breeding stallions often are expected to breed multiple mares daily at the peak of breeding season. To that end, veterinarians and stud managers hope to optimize stallions’ sperm quality and quantity and, thus, pregnancy rates. Researchers recently sought to determine the effects of a human drug designed to improve blood flow on stallions’ semen quality and testicular blood flow.

"To successfully breed this many mares, stallions must consistently produce large numbers of good-quality sperm," explained Malgorzata Pozor, DVM, PhD, Dipl. ACT, an assistant clinical professor in the University of Florida’s College of Veterinary Medicine.

Complicating this requirement are many factors that can adversely affect sperm production, such as age, illness, anabolic steroid use, trauma, and testicular degeneration. And since declining fertility contributes to significant financial losses, the issue of optimizing sperm quantity and quality can be crucial for breeders.

"In humans, a drug called pentoxifylline has improved sperm motility, shape, and concentrations, presumably by improving blood flow in the testicles," said Pozor