Stallion Fertility Fine Following Removal of One Testicle (AAEP 2012)

Stallion Fertility Fine Following Removal of One Testicle (AAEP 2012)

Researchers found that sperm quality was not negatively impacted by the removal of one testis in the immediate postoperative period.

Photo: Courtesy Dr. Krishona Martinson/University of Minnesota

If your stallion needs to have a testicle removed due to disease, neoplasia (tumor), or severe trauma, don't worry: Stallions can still lead productive lives as studs with only one testis, assures a researcher from Texas A&M University.

"Clinical experience suggests that unilateral orchiectomy of a diseased or traumatized testis is fairly common in breeding stallions," said Justin McCormick MS, DVM, of the school's Department of Large Animal Clinical Sciences, in his presentation at the 2012 American Association of Equine Practitioners' Convention, held Dec 1-5 in Anaheim, Calif.

McCormick explained that even wasn't clear if sperm quality decreases following the removal of one testis, the research community recommends sexual rest for at least one spermatogenic cycle (about 12 days). However, a postoperative period of sexual rest following unilateral castration during the breeding season can negatively impact a stallion's economic productivity due to lost breeding opportunities.

McCormick and his colleagues compared two different unilateral castration procedures to determine if one technique was more damning on sperm quality than the other.

"We performed unilateral castrations on nine Miniature Horse stallions using either a 'first intention' or a 'second intention' procedure to close the scrotum," explained McCormick.

First-intention healing means that the surgical incisions created to remove the affected testicles were sutured closed, and second-intention healing means that the incisions were left open to drain.

McCormick and his colleagues evaluated semen quality, scrotal and body temperatures, testis size, and incision healing for 60 days following surgery (approximately five breeding cycles).

Their key findings:

  • Sperm quality was not negatively impacted by the removal of one testis in the immediate postoperative period;
  • There did not appear to be a difference in sperm quality throughout the study whether the incisions were closed or left open to heal by second intention;
  • Incisions that were closed healed faster, potentially allowing stallions to return to breeding sooner; and
  • In this group of Miniature Horse stallions, compensatory hypertrophy (i.e., an increase in size of the remaining testicle to compensate for the "lost" testicle) occurred by Day 30, which was earlier compared to previous reports.

"An extended period of postoperative rest of 60 days or more was not supported in this group of Miniature Horse stallions. Instead, breeding soundness may be more impacted by pre-existing abnormalities in the inguinal area than surgical trauma and healing," McCormick concluded.

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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