First successful reverse vasectomy on endangered species performed at the Na...(ctomies in South American bush dogs at t...)

"Although our team is very experienced in horse anesthesia and surgery, by using the specialized professional skills of Dr. Silber, we greatly increased the likelihood of success," said Dr. Luis Padilla, associate veterinarian at the Conservation and Research Center.

Silber, working with the Zoo's team of veterinarians and reproductive scientists, first performed the operation on Minnesota in March 2007. That procedure proved unsuccessful, possibly due to the presence of scar tissue or the fact that the horse was positioned on its side, making it difficult to perform the surgery. Silber was confident that if the horse could be placed on its back, the procedure would be a success. Laying an anesthetized horse on its back for a prolonged period of time can be challenging due to their size and physiology. Veterinarians decided it could be done, but only if the surgery time was kept to a minimum. In October 2007, the team operated on Minnesota againcompleting the procedure in an hour. Six months later, the Zoo's veterinarians and reproductive scientists collected a semen sample from the horse that indicated the procedure had been a success.

"I've always dreamed of using my expertise to contribute in some way to wildlife survival," said Dr. Silber. "It was exciting to pioneer a new procedure for which humans were the 'test animal.'"

National Zoo scientists hope to pair Minnesota with a suitable female in July. His genes will infuse genetic diversity in a Przewalski's horse population that is based on genes from only l4 original animals. National Zoo scientists are researching ways to improve fertility and produce more offspring in the aging, captive population. Bolstering the population translates into more horses for future reintroduction programs, essential for a critically endangered species. Currently, National Zoo scientists are working in remote areas of China using r
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