Veterinary researchers publish scores of scientific papers annually, but if practitioners are out examining and treating patients they don’t necessarily have time to brush up on every study’s take-home message. The annual Kester News Hour presentation at the American Association of Equine Practitioners’ convention gives practitioners a chance to sit down with a coffee and hear veterinary specialists summarize of a year of studies. Pat McCue, DVM, PhD, Dipl. ACT, gave a rundown on a number of the year’s practical equine reproductive studies during the 2012 convention, which was held Dec. 1-5 in Anaheim, Calif.

Stallion/Semen/Sperm

McCue, a professor of equine theriogenology at Colorado State University’s Equine Reproduction Laboratory, first described a paper by Terry Blanchard, DVM, MS, Dipl. ACT reviewing issues in older stallions with testicular dysfunction. Owners and veterinarians’ goal for these horses is to maintain them in a successful breeding program, be it using natural cover or artificial insemination (AI).

McCue described the natural progression in decreased testicular function: decreased sperm production; decreased first-cycle pregnancy rates; then spermatozoa changes such as declines in morphologically normal and progressively motile sperm. He also noted that toward the end of a stallion’s career, due to testicular degeneration, the testes decrease in size with accompanying endocrinological changes. Hormone levels (e.g., estradiol, inhibin, and testosterone) decrease, leading to reduced signals that would normally affect gonadotropins (protein hormones) such as follicular stimulating and luteinizing hormones