Study: Pentoxifylline's Effect on Semen Quantity and Quality

Study: Pentoxifylline's Effect on Semen Quantity and Quality

Pentoxifylline did not seem to improve semen quality or quantity in horses, the researchers found.

Photo: Anne M. Eberhardt/The Horse

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.

To determine if pentoxifylline had similar beneficial effects in horses, Pozor and colleagues administered 17 mg/kg pentoxifylline to three Miniature Horse stallions for 60 days. Another three pint-sized stallions served as the untreated control group.

Pozor found that:

  • Pentoxifylline administration delayed the normal seasonal decrease in testicular blood flow as determined by measuring blood flow and the diameter of the blood vessels in the stallions' testicles; and
  • Sperm quality and quantity were not significantly improved with pentoxifylline administration.

"It is possible that a longer treatment period or a higher dose of pentoxifylline is needed to see a beneficial effect," Pozor noted.

Pozor noted a concerning aspect of the study was that all three test stallions develop a mild hydrocele--an accumulation of clear fluid in the scrotal sac around the testicle--during the treatment period.

According to Pozor, "Mild hydroceles are not thought to have any significant effect on stallion fertility; however, they should not be ignored and this could be an important complication associated with pentoxifylline in horses."

The study, "Effect of pentoxifylline treatment on testicular perfusion and semen quality in miniature horse stallions," will be published in an upcoming edition of the journal Theriogenology. The abstract is currently available on PubMed.

About the Author

Stacey Oke, DVM, MSc

Stacey Oke, MSc, DVM, is a practicing veterinarian and freelance medical writer and editor. She is interested in both large and small animals, as well as complementary and alternative medicine. Since 2005, she's worked as a research consultant for nutritional supplement companies, assisted physicians and veterinarians in publishing research articles and textbooks, and written for a number of educational magazines and websites.

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