First successful reverse vasectomy on endangered species performed at the Na...( Veterinarians at the Smithsonian's N...)

Veterinarians at the Smithsonian's National Zoo have performed the first successful reverse vasectomy on a Przewalski's horse (E. ferus przewalskii; E. caballus przewalskii classification debated), pronounced zshah-VAL-skeez. Przewalksi's horses are a horse species native to China and Mongolia that was declared extinct in the wild in 1970. Currently, there are approximately 1500 of these animals maintained at zoological institutions throughout the world and in several small reintroduced populations in Asia. This is the first procedure of its kind to be performed on an endangered equid species.

The genes of Minnesotathe horse who underwent the surgeryare extremely valuable to the captive population of the species, which scientists manage through carefully planned pairings to ensure the most genetically diverse population possible. The horse was vasectomized in 1999 at a previous institution so that he could be kept with female horses without reproducing. He came to the National Zoo in 2006.

While surveying the captive North American population of Przewalski's horses, scientists realized Minnesota's genetic value. Based on his ancestry, he is the seventh most genetically valuable horse in the North American breeding program. Zoo scientists were confident that if they could successfully reverse the vasectomy, Minnesota would be able to sire a foal through natural mating.

"The major challenge we faced was that this procedure had never been performed on an equid, let alone a critically endangered species," said Dr. Budhan Pukazhenthi, a reproductive scientist at the National Zoo's Conservation and Research Center in Front Royal, Va. "We had to develop all new protocols ourselves."

The team sought the expertise of Dr. Sherman Silber, a St. Louis-based urologist who pioneered microsurgery for reverse vasectomies in humans and had been successful in vasectomizing and then subsequently reversing vase
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