April 29, 2005
Zoo Reverses Vasectomy on Bush Dog
ST. LOUIS (AP) -- Three yapping, cuddly South American bush dog pups at the Saint Louis Zoo are making fertility history among wild canids, with implications for the rest of the animal world.
Youngsters Mariana, Turi and Sherman, resembling chubby, furry, Chihuahuas, were born in January following a successful, first-of-its-kind vasectomy reversal on the pups' father. The procedure was performed in August 2003 by St. Louis infertility specialist, Dr. Sherman Silber, a 15-year zoo consultant, who perfected it on more than 4,000 humans before trying it on Brent, the bush dog.
The reversible vasectomy holds the best hope for the world's zoos to manage animals genetically and behaviorally, said Ingrid Porton, the Saint Louis Zoo's primate curator. She also is codirector of the American Zoo and Aquarium Association's Wildlife Contraception Center in St. Louis.
"It allows us to manage reproduction in a responsible way, and meet (animals') behavioral and social needs," Porton said. "It's so much more preferable not to isolate animals to prevent breeding; with a reversible contraception, we can allow them to live in a social group."
The idea for a reversible, non-chemical form of contraception for males came out of a St. Louis study of female bush dogs' reproductive habits, and required having four males - Brent among them - not producing sperm. Silber, assisted by zoo veterinarians, performed the reversible vasectomies in January 2002.
The researchers wanted the mating behavior but not for the females to get pregnant because once they stop being in heat, they'll refuse males, said Dr. Randall Junge, the zoo's director of animal health.
"Vasectomies allowed (the males) to maintain reproductive behavior but stop the fertility," he said.
Chemical contraception that shuts down testosterone production is not ideal because it alters behavior, Porton said.
At the end of that study, Silber and zoo vets reversed the vasectomies, and the effectiveness of the reversal was tested on Brent.
The proof is his three yelping pups, which likely will go on public display next week at the Saint Louis Zoo. Porton said she is unaware of vasectomy reversals of other zoo species in the world.
Dr. Cheri Asa, the Saint Louis Zoo's director of research, has said contraception allows for controlled pairings, or "high-tech matchmaking," that maintains the animals' genetic diversity, prevents inbreeding, and permits individuals to live in natural social and family groups.
Silber, who performed his first vasectomy reversal on a human male in 1981, said he modified the procedure slightly for the bush dog, and would for other exotics as well. He called both the vasectomy and its reversal simple procedures that can be taught easily to veterinarians. He performed a reversible vasectomy on a chimpanzee a month ago at the Tulsa Zoo.
Male bush dogs are not only sharing the responsibility of contraception, they wholeheartedly share in parenting, too, zoo experts said.
"There is no more involved wild canid parent than the bush dog," Porton said. They clean the female and pups after birth, and even have been observed acting as midwife, by pulling a pup from the birth canal, she said.
On Tuesday, after the pups were vaccinated and weighed, they returned to their waiting parents in the Saint Louis Zoo's makeshift den, where the pups pawed at their dad's mouth to indicate they were hungry. He chews their food before giving it to them.
Bush dogs are about the size of a terrier, with short legs and a short tail, and webbed feet that enable them to chase prey in the water. They live in packs, eat large rodents, and dig burrows.
Brent was born at the Little Rock Zoo in 2000 and arrived in St. Louis in 2002, when he was paired with Foosa. She was born on St. Maarten in the Caribbean in 1999.
On the Net:
Saint Louis Zoo: http://www.stlzoo.org/