Maryland Zoo officials say they're still puzzled by the death of a 23-year-old chimpanzee during an examination Thursday.
"This was quite sudden and not something we were expecting," Rebecca Gullott, the zoo's mammal collection and conservation manager, said yesterday. "This was a very sad occasion for us because we develop strong bonds to the animals we care for."
Since Sunday, Rustie, the largest of 11 chimps in the zoo's troop, had been lethargic and reluctant to eat, zookeepers said. After her symptoms persisted and she refused oral antibiotics, she was anesthetized for an exam.
Within minutes, keepers said, Rustie stopped breathing. Zookeepers performed CPR, but their attempts to revive the chimp failed.
"Anesthesia is always a risk - in humans and in our animals. It's something we contemplate and weigh the risks and benefits," said Dr. Ellen Bronson, the zoo's senior veterinarian. "Most of the time, the anesthesia goes fine, and it's something we're very careful about."
Complications from anesthesia can occur at any age, Bronson added. "Her death couldn't have been prevented. It was a part of her illness," she said.
Bronson speculated that an abnormal growth at the back of Rustie's throat obstructed her airway during anesthesia and was the immediate cause of death. Pathologists at the Johns Hopkins University are performing a necropsy, but the results won't be available for three weeks.
"These growths can happen very quickly, and it just shows that these events do happen through physical illness sometimes," said Steve Ross, chair of the Chimpanzee Species Survival Plan (SSP) of the American Zoo and Aquarium Association. The SSP helps manage the 300 chimpanzees living in accredited zoos across North America.
The association has threatened the zoo's accreditation this year, largely because of physical plant problems.
But Ross, who visited the zoo two years ago and was unaware of its accreditation issues, said that he was happy with the chimp exhibit. "I feel confident in the care that chimps get at the Maryland Zoo," Ross said. "I have visited a lot of zoos - not all zoos in SSP - but I have visited Maryland, and I know the people there. And I know that it wasn't a case of poor care."
The other 10 chimps in the troop appear to be in good health, Bronson said.Chimps typically live until their mid-40s, which made Rustie "middle-aged," according to Gullott.
Rustie, who came to the zoo in 1995 from Yerkes National Primate Research Center in Atlanta, had two daughters: 13-year-old Raven and 3-year-old Rozi. Both live in the zoo.