Robust gorillas mysteriously dying in zoos

By Todd Lewan

updated 1:47 p.m. ET April 6, 2008

Mopie looked the picture of ape fitness: His shoulders were broad and imposing, his silver-haired back sculpted and muscular, his biceps bulging as wide as a wrestler’s thighs when he scratched his head.

He had a healthy appetite (he’d put away 7 pounds of food daily) and Mopie was no couch gorilla, either: He’d nimbly scale the mesh of his enclosures at the National Zoo in Washington, D.C., playfully chase the younger gorillas, and perch himself high in an outdoor maple, as if to show the world he was the king of the Great Ape House.

“The unique thing about Mopie was how extremely handsome he was,” says Lisa Stevens, curator of primates and giant pandas at the National Zoo, and whenever the silverback sat, proudly, in the exhibit’s trees, “it just added to his impressiveness.”

Which is why Stevens and the zoo’s staff were so stunned when, on the afternoon of July 3, 2006, this prized western lowland gorilla suddenly collapsed after playing with some newly introduced mates. By the time the keepers cleared out the other gorillas and tried CPR on Mopie, the gentle, 430-pound giant was lifeless — a victim of heart failure at 34.

Like his father, who had died the same way at the zoo in the early 1990s, Mopie had previously been diagnosed with an unexplained form of heart disease known as fibrosing cardiomyopathy, in which healthy heart muscle turns into fibrous bands unable to pump blood. And yet, he had not shown any outward symptoms, and his diet and behavior were normal.

“There was nothing to indicate he was feeling poorly or under the weather,” recalls Stevens. “That’s what made it even more of a shock.”

No less troubling, two days earlier the National Zoo had lost its only other male group leader, a silverback named Kuja. Diagnosed just a month earlier with congestive heart failure related to cardiomyopathy, Kuja (pronounced KOO-yah) died while undergoing surgery to receive an advanced pacemaker. He was 23.

Sadly, Mopie and Kuja were not alone.

Nationwide trend
Gorillas in zoos around the nation, particularly males and those in their 20s and 30s, have been falling ill — and sometimes dying suddenly — from progressive heart ailments ranging from aneurisms to valvular disease to cardiomyopathy.

Just two months before the deaths at the National Zoo, the San Francisco Zoo had lost a lowland gorilla named Pogo to heart disease. A week before that, the Memphis Zoo lost one named Tumai the same way. And in previous years, there were others: Akbar at the Toledo Zoo in 2005, and in 2000 both Sam at the Knoxville Zoo and Michael at the Gorilla Foundation in California.

Frank Couch / AP Babec, a male silverback gorilla, is rolled out of the operating room in March 2005 after having a pacemaker replaced at the Birmingham Zoo's Animal Health Center. He was the first gorilla to ever have the device implanted. Also pictured: Dr. Anna Ogburn, left, Marcia Reidmiller, second left, Jeff Cook and Beth Severson, right.

Now zookeepers are scrambling to understand what factors may be causing the illnesses and what might be done to save the 368 lowland gorillas that currently reside in 52 zoos across North America.

A 1994 study of 74 captive gorilla deaths, published by veterinarians Tom Meehan of the Brookfield Zoo in Chicago and Linda Lowenstine of the University of California at Davis, found that 41 percent — and 70 percent of males older than 30 — were from heart disease, mainly fibrosing cardiomyopathy.

“That study was a wake up call,” says Meehan, now the vice president for veterinary services at the Chicago Zoological Society. It showed the need to “go to the next level of evaluating the animals and figuring out how their lifestyle related to their health.”

In the mid-1990s, when the study was published, about 100,000 western lowland gorillas roamed freely within vast forests in Cameroon, the Central African Republic, the Republic of

INTERACTIVE Zoo babies Check out a cuddly gorilla baby, a ‘hideously cute’ aardvark cub — and the other new kids in captivity!

Congo, Equatorial Guinea, Gabon, Angola and Nigeria. Far less endangered than their relatives, the mountain gorillas, these apes were officially considered only as “vulnerable.”

Since then, however, lowland gorillas in the wild have been dying at an accelerating rate. Poaching, logging, a dramatic expansion in the trade of bushmeat, and outbreaks of Ebola have reduced their numbers to roughly 30,000 — and in September, the species was reclassified as “critically endangered.” At their current rate of decline, the gorillas are projected to disappear from the wild by 2050.

“Soon, these great apes may only exist in captivity,” says Haley Murphy, director of veterinary services at Zoo New England, which runs Boston’s Franklin Park Zoo and the Stone Zoo in Stoneham, Mass. The zoos are home to seven western lowland gorillas, the only species kept in captivity.

In 2000, Murphy, together with Dr. Ilana Kutinsky, a cardiologist with the Michigan Heart Group, began reviewing cardiac ultrasounds of zoo gorillas in hopes of discovering why the animals were at risk for heart trouble. It was part of a broad, veterinary detective effort to help save what Murphy calls “our closest living relatives, evolutionarily.”

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