Nowadays, an actively competing stallion in the United Kingdom can sire a foal in California without the mare ever leaving the state. International distribution is just one of the ways frozen semen is helping breeders around the world. But how can veterinarians take fresh semen, freeze it solid, ship it, and then wake the sperm back up? It’s a complex process.

At the 2016 Western Veterinary Conference, Heath King, DVM, Dipl. ACT, shared how veterinarians can implement frozen semen processing in their practices by outlining the steps and reviewing techniques. King is an assistant clinical professor of theriogenology at the Mississippi State University College of Veterinary Medicine, in Starkville.

In addition to creating a global breeding market, frozen semen allows breeders to keep genetic lines alive after a stallion dies or is unable to physically breed any longer, eliminates the need to transport mares long distances for insemination, and eases scheduling difficulties that arise with fresh or cooled semen or live cover, King said.

But it’s not without its drawbacks. For example, processing, shipping, and storing frozen semen can be costly, and not all stallions’ semen can be frozen successfully.

“Tremendous variations in freezability exist among stallions, the cause of which is not known,” King explained. “Generally, when post-thaw motility (or movement capability) is compared, 25% of stallions freeze well, 50% freeze fair, and 25% freeze poorly.

“There is also a subset of stallions that appear to freeze well based on their post-thaw motility, but are unable to produce a pregnancy with f