Zoos across the U.S. struggle to care for aging animals

The Cheyenne Mountain Zoo lost a cherished senior citizen recently when Maggie, a 34-year-old Nile hippopotamus, was euthanized.

She was definitely in her golden years for a hippo, but Maggie was just a kid compared with Bert, a hippo at the Denver Zoo that will celebrate his 52nd birthday in August.

The 2-ton Maggie had been in failing health for a year, suffering from arthritis and weight loss. Bert also suffers from joint problems and receives hippo-size doses of arthritis medication, said Felicia Knightly, an associate veterinarian at the Denver Zoo. He also has some dental issues, she said, but still eats well.

"More and more, you need to be a good geriatric practitioner," Knightly said. "People don't realize how long these animals live in captivity and some of the problems they face."

   The Golden Years have arrived at the nation's zoos and aquariums, and that is taking veterinarians and keepers, along with their animals, into a zone of unknowns.

   Do female gorillas, now frequently living into their 40s and 50s, experience menopause?

   Can an aging lemur suffer from dementia?

   How do you weigh the most difficult choice - between prolonging pain and ending life - when the patient is a venerable hippo who's been around so long she's come to feel like a member of the family?

   All those questions hang on a larger one that, until recent years, has been left to educated guesswork based on limited evidence.

   "How old is geriatric? How old do animals really live?" says Sharon Dewar, a spokeswoman for Chicago's Lincoln Park Zoo. "That's the million-dollar question."

   Zeroing in on the answers takes years of tracking the birth, death and age of animal populations. Zoos, which have pooled information on animal births and genealogy since the 1970s, are drawing some early conclusions. For example, records show that the median age of Siberian tigers living in zoos in the two decades ending in 1990 was a little over 11 years old. Since then, however, the median age of those tigers has topped 15 years.

   The increase in animal longevity is no mystery. Just as with people, health care for animals has become much more sophisticated.

   At the San Antonio Zoo, keepers noticed that George, a 37-year-old tapir, was slowing down. In the mornings, his legs seemed stiffer, and he had trouble getting up. The diagnosis was clear: arthritis.

   At first they put him on dietary supplements. They moved on to Adequan, a prescription that helped ease the discomfort further. Still, wasn't there more they could do? The problem is there's no textbook for how to treat a geriatric tapir.

   Reasoning that tapirs are not so different from horses, the zoo called in a specialist who performed acupuncture on George, inserting tiny needles at various medians to ease the pain.

   Since then, George "acts like he's five years younger," says Rob Coke, the zoo's senior staff veterinarian.

   Keepers focus on more than just keeping animals healthy. They create habitats and social environments that will make them happy and less-stressed.

   The result is more robust animals, with the potential to live longer. That potential is realized because life in a zoo or aquarium grants animals an exception to nature's laws of survival.

   "There are no predators," said Tracy Leeds, general curator at the Cheyenne Mountain Zoo. "They have vet care. If they don't feel good, we take care of them. They get fed every day, they don't have to go look for food."

   The Cheyenne Mountain Zoo has lost some of its most revered senior citizens in the past year. Maggie died in May. Sandra, a 51-year-old Sumatran orangutan, died in her sleep in December; she was the third-oldest orangutan in any U.S. zoo. And Laikipia, head male in the zoo's world-renowned herd of reticulated giraffes, was euthanized last summer after being plagued for years by degenerative disease. Though his exact age wasn't known, he was about 25.

   A few old-timers are still around, though. Becky, a giraffe, is 27 - "definitely geriatric," said Jason Bredahl, the zoo's elephant and giraffe manager. One of the zoo's African penguins, Jess, just celebrated her 28th birthday. In the wild, the African penguin's average life span is 15 to 20 years.

   Such longevity confronts zoo managers with mysteries and doubts they've never really had to deal with before.

   "The simple question was: ‘Does a 41-year-old gorilla need to be on birth control?' And nobody really knew," says Sue Margulis, curator of primates at Lincoln Park.

   The question applies to far more than the one gorilla at Chicago's Brookfield Zoo. When Margulis and a fellow researcher set out to study the possibility of menopause in gorillas, they looked at 30 gorillas in 17 zoos around the country. Of those, 22 are considered geriatric, including one who's now 55.

   They found that about a quarter were no longer going through monthly menstrual cycles, while others were in transition. But while gorillas in menopause spent much less time with the male silverbacks, most were quite healthy. In the wild, female gorillas typically leave the group in which they're born. In zoos, older female gorillas stick around, sometimes playing a grandmother role in child care that is likely unique to captivity.

   At the St. Louis Zoo, the uncertainties of aging have keepers wondering about the well-being of Ruffes, a 31-year-old black-and-white ruffed lemur.

   Some of Ruffes' problems are easily identifiable and treatable. For example, he gets an anti-inflammatory pill twice a day to combat the pain of spinal arthritis.

   But there's no easy diagnosis for another symptom. At times, Ruffes seems to be staring off into nowhere.

   "Dementia is one of those things that's very difficult to pin down just because we can't use the same sort of testing as we do with humans," says Joe Knobbe, St. Louis' zoological manager of primates.

   The best that keepers can do is make him comfortable, including installing a tiny hanging platform where Ruffes enjoys resting with a blanket.

   Many zoos have made similar changes to animal habitat to ease life for geriatric residents.

   At the Cheyenne Mountain Zoo, staff members tend to Dakota the mountain lion's aches and pains. At age 18, Dakota receives pain and arthritis medications and is provided soft bedding.

   "With Dakota, we don't do high perches anymore," Bredahl said. "We don't want to encourage her to climb."

   Blossom, a mountain lion at the Denver Zoo who's a couple of years older than Dakota, also receives arthritis medication. It's clear, Knightly said, that Blossom's hearing and vision are not as sharp as they were, and the big cat seems to show a bit of senility at times.

   "You have to be like, ‘Hello, look at me,'" Knightly said.

   "But I still think she has a good quality of life. She still eats every day and loves to lay out in the sun."

   The challenge is deciding what to do when quality of life ebbs away - and how to gauge that. In the wild, survival requires animals to cover up weaknesses and infirmities. But keepers who spend years watching these animals sense when something is wrong.

   "The keepers work with them every day," said Leeds, the Cheyenne Mountain Zoo curator. "They notice really subtle differences."

   Keepers kept a close eye on Maggie the hippo for a year before the decision was made to euthanize.

   Though Maggie continued to eat, she lost weight and seemed to be in increasing pain.

   "We started seeing she wasn't quite herself," said Roxanna Breitigan, animal care manager. "We kept really good track every day how she was. Over time, she was not better."

   The decision to end Maggie's life - and thus her suffering - was a group decision involving Leeds, keepers, the vet staff and even the zoo's chief executive offcer.

   "With Maggie," Breitigan said, "we all agreed that it was the right decision."