Zoo in a life-or-death race

Tess, a 26-year-old Asian elephant due to give birth in the fall, and her 4-year-old calf Tucker, left, get treats Thursday after taking a walk around their enclosure at the Houston Zoo.The last 14 Asian elephants born in Houston have died, but now there’s hope for a vaccine,

It's stork time at the Houston Zoo's elephant barn as the maternity countdown begins for Shanti and Tess, endangered Asian elephants whose pregnancies, officials hope, will bring success to a pachyderm breeding program thus far marked by failure.

Zoo officials Thursday staged a maternity “boot camp” in which they outlined efforts to ensure live births and the survival of the calves. In 25 years of zoo breeding efforts, all 14 calves died before or relatively soon after birth.

Six of the calves — most recently Max, who died at age 2 in November 2008 — succumbed to a disease caused by a herpes virus.

“We have lots of concerns,” said Daryl Hoffman, the zoo's large mammal curator. “As we learn more, our success rates should improve. Every one that we lost was under different circumstances.”

Last year, the Houston Zoo and Baylor College of Medicine joined forces to develop a vaccine to protect against the herpes illness, which causes blood vessels to leak and can lead to heart failure.

Dr. Paul Ling, associate professor of molecular virology and microbiology, said an effective vaccine still may be five years away. But researchers have created a successful test for the virus, thereby allowing for treatment of infected animals before the deadly disease develops.

Four of the zoo's five Asian elephants, including Shanti and Tess, have tested positive for the virus. The virus is most dangerous to elephants younger than 10 years, and Shanti, 19, and Tess, 26, are well past that age. It is not known whether they can transmit the virus to their young in the womb. As virus carriers, however, they can transmit it after the calves are born.

Other U.S. zoos affected

The pregnant elephants' bodily fluids are tested weekly for virus and hormone levels. As their delivery dates approach — Shanti is expected to give birth this spring, Tess in the fall — testing will be conducted twice weekly, then daily.

The animals' blood pressure will be checked through cuffs attached to their tails. As the big day approaches, the mothers-to-be will be subjected to ultrasound scans to determine the fetuses' position.

As many as 40 volunteers will become involved before and after the births as the animals are monitored 24 hours a day, Hoffman said.

Hoffman said the zoo's goal is to create a self-sustaining elephant population. The animals typically live more than 40 years, he said.

At this stage of the pregnancies, Hoffman said, both Shanti and Tess are being placed on stringent dietary and exercise regimens to help them shed their extra “baby weight.”

Houston Zoo spokesman Brian Hill said elephant breeding programs at other American zoos also have been affected by the virus. Some of the infected animals have survived with treatment, however, most recently a calf born last year in St. Louis.

The World Wildlife Fund says the free-roaming Asian elephant population has been decimated by human-pachyderm interactions and habitat loss. Twenty percent of the world's population lives near elephant habitats, the advocacy group says, and animals that intrude into areas occupied by people often are killed. Male elephants also are slaughtered for their ivory tusks.

No more than about 33,000 Asian elephants exist in the wild, the organization reports.

Leigh Henry, a senior policy officer with the fund's species conservation program, said her organization “sees value” in captive breeding programs as long as the breeding stock is not taken from the wild.

‘Ethical thing to do'

But Catherine Doyle, captive elephant specialist with In Defense of Animals, a California-based advocacy group, described the Houston Zoo's breeding efforts as “unconscionable.”

The zoo should shut down its elephant breeding program, Doyle said.

“It's the ethical thing to do,” she said. “Fourteen elephants have been born to the zoo and not one is alive today. … This is a horrific disease that brings terrible suffering before death.”