Archived News

UC Davis Veterinarians Successfully Utilize 20-Year-Old Frozen Canine Semen

March 1, 2015

What's New Image

UC Davis' Theriogenology Service helped Maizie deliver four healthy puppies produced from 20-year-old frozen semen.

VMTH "Case of the Month" - March 2015

Maizie, a 2-year-old border terrier, was recently treated by the UC Davis Veterinary Medical Teaching Hospital’s Theriogenology Service for breeding management. Maizie’s owner, Elizabeth, is a nationally recognized border terrier breeder with more than 40 years of experience with the breed. She has had great influence on the quality of this English breed’s presence in the United States. Border terriers are not common in the U.S., but make wonderful family companions.

Elizabeth had special plans for Maizie’s breeding. Twenty years prior, she owned a spectacular male border terrier named Remy. He was an important sire and nationally recognized show dog for the breed in the U.S., with excellent structure, movement and temperament. During his life, Remy produced 44 champions, and was considered one of the foundations of border terriers in America. His semen was collected and frozen in 1994, with the hopes of using it later on a quality female border terrier. Elizabeth waited 20 years to find just the right match—Maizie—for Remy’s frozen semen. 

Using frozen semen to result in a successful breeding is a delicate process. It carries a much lower conception rate than the average breeding with fresh or chilled semen. Frozen semen must be used precisely because it is inherently more fragile, and has shorter longevity to result in fertilization of an egg. Although it is more challenging to use successfully, frozen semen breedings can greatly benefit the dogs of excellent breed merit and health. Male dogs from years past can enrich breeding programs happening present day. It also allows for international transport of genetics and a broader genetic pool for those breeds fewer in number in the U.S. Semen exceeding 30 years since freezing has successfully been used in dogs, and the potential for hundreds of years of longevity has been suggested.

The Theriogenology Service routinely saw Maizie during her heat cycle to evaluate her for optimal time of breeding. Testing included evaluation of her vaginal cytology, progesterone testing, and visual evaluation of her vaginal canal. Using these clues, the best possible window for optimal conception with frozen semen was established. On the day Maizie was most fertile, the semen was thawed and placed into her uterus.

Approximately one month later, an ultrasound was performed on Maizie to evaluate for a pregnancy. Four healthy fetuses with heartbeats were seen growing in early pregnancy. At term, the puppies were delivered by a planned C-section, all with excellent health and vigor.

The litter has been growing and thriving since delivery, receiving regular check-ups at the VMTH, including vaccination and deworming. Maizie took to motherhood immediately, regularly tending to her puppies’ needs. Having come from such desired stock, the puppies may have great influence in carrying on the breed characteristics of the border terrier for generations to come.

About the Veterinary Medical Teaching Hospital
The William R. Pritchard Veterinary Medical Teaching Hospital at the University of California, Davis—a unit of the School of Veterinary Medicine—provides state-of-the-art clinical care while serving as the primary clinical teaching experience for DVM students and post graduate veterinarian residents. The VMTH treats more than 47,000 animals a year, ranging from cats and dogs to horses, cows and exotic species. To learn more about the VMTH, please go to Timely news updates can be received on its Facebook ( and Twitter ( pages.

Rob Warren
VMTH Communications & Marketing Officer