June 24, 2008

Historic Equine Reverse Vasectomy Reported

U.S. veterinarians at the Smithsonian's National Zoo say they have performed the first reverse vasectomy on an endangered equine species.

The procedure was performed on a Przewalski's horse. That species, native to China and Mongolia, was declared extinct in the wild in 1970. Currently, there are approximately 1,500 of the animals maintained at various zoological institutions and in several small reintroduced populations in Asia.

The veterinarians said the genes of the horse named Minnesota are extremely valuable for ensuring the most genetically diverse population possible. A vasectomy was performed on Minnesota in 1999 at a previous institution so he could be kept with female horses without reproducing. He was sent to the National Zoo in 2006.

The veterinarians subsequently discovered, based on his ancestry, Minnesota is the seventh most genetically valuable horse in the North American breeding program.

After one failed operation in March 2007, they conducted a second procedure last October. Six months later a semen sample indicated the procedure had been successful.

National Zoo scientists hope to pair Minnesota with a suitable female next month, saying his genes will infuse genetic diversity in a Przewalski's horse population that is based on genes from only 14 original animals.