Deaths of Big Cats Leave a Legacy of Questions, Fears : Animals: Wildlife refuge reopens after being besieged by baffling outbreak of canine distemper.

Brutus was the first big cat to go down.

The fierce-eyed black leopard dropped quickly one afternoon last September as though some hunter’s bullet had suddenly ravaged his crouched and panting body.

Then Doris fell victim. Like Brutus, she sprawled helplessly in her cage, chest heaving, eyes as wild as the Serengeti.

In days both were dead; Brutus shaken by a powerful seizure, a comatose Doris euthanized by veterinarians helpless to do more.

Just like that, Martine Colette and the staff at the Wildlife Waystation, a refuge for exotic animals in Little Tujunga Canyon, were posed with a puzzling medical mystery: their big-game predators were falling prey to a perplexing, uncontrolled disease.

Swiftly, researchers pinpointed the killer as the canine distemper virus, a common airborne micro-organism not normally found in cats.

But larger riddles continued to baffle the nation’s top animal researchers: Why did the virus jump species to affect the big felines? And could it be stopped? Despite elaborate precautions that included a full quarantine, the disease waged its lethal spread. As autumn crept by, the lions, tigers, leopards and jaguars continued their strange procession toward death.

“We felt absolutely powerless,” Colette said of her five-month battle against the virus and her fears. “We tried everything to find out what was affecting these cats. But no matter what we did, they continued to die--one magnificent creature after another.”

Months later, in early January--with the euthanizing of Tibor the tiger--the dying stopped, but not before the disease took 17 felines.

No one knows whether the virus was confined to the rural compound or whether it will surface at nearby zoos. Nonetheless, the Los Angeles Zoo has since begun to vaccinate its big cat population and other facilities plan to do the same.

Scientists agree that the case will go into veterinary textbooks as a medical anomaly--the first widespread outbreak of the common animal virus among exotic cats.

For the first time since late September, the nationally known center will lift its quarantine today, allowing scores of volunteers to return and tend to the grizzly bears, wolf packs, alligators, chimpanzees, toucans and hyena.

Life at the compound has returned to its screaming, hooting, growling, howling self. For now.

Brutus the leopard, who had survived years of frustration as a circus performer, died a painful death. And veterinarian Rebecca Yates wanted to know why.

She had performed an autopsy on the leopard and found no abnormalities. Then she sent off samples of his frozen tissue to researchers at UC Davis for comparison with the remains of the lioness Doris.

Under the microscope, doctors found an odd similarity: submicroscopic lesions in the brain and lungs of both animals.

Then Yates got a call from Dr. Mark Anderson, a UC Davis diagnostic pathologist, suggesting the unthinkable.

“If I didn’t know any better,” he said with a guarded laugh, “I’d say this was a case of canine distemper.”

If true, it would be a twist to send Sherlock Holmes scrambling for Dr. Watson: the wildlife refuge under siege from an illness common to dogs that had unaccountably jumped species to attack the large cats.

Yates recalled a 1983 article detailing an isolated case in which a Bengal tiger in Oregon had mysteriously contracted the virus. “I told him we might be on to something,” she said. “I mean, at that point, we couldn’t rule anything out.”

Both veterinarians immediately knew their next move. They called Dr. Max Appel of the New York State College of Veterinary Medicine at Cornell University, a world-renowned source on viral infections who had previously isolated the canine distemper virus in feline tissue.

They were in luck. Appel quickly confirmed that both animals had contracted the canine distemper virus. He also had recently prepared a batch of the killed canine distemper virus for use as a vaccine. Veterinarians decided to inject each of the compound’s big cats with the vaccine in the hopes of heading off the rampant virus.

Appel shipped the frozen vaccine by overnight mail, along with a stern warning: Do not expect any miracles, especially if the cats had already been exposed to the airborne microorganism.

Within hours after the virus was identified, Martine Colette called a meeting at the refuge to make some hard decisions.

Soon the entire compound, home to more than 750 abandoned and orphaned wild animals in Angeles National Forest, was under quarantine. The twice-monthly tours were canceled. Only necessary workers were allowed inside the 160-acre refuge.

Colette, who founded the nonprofit center in 1969, notified area zoos--as well as local, state and federal health agencies--that an unpredictable animal virus was on the loose.

At all hours, she was continually awakened at her home on the refuge grounds to learn of a new cat falling ill from seizures, diarrhea, coughing fits and respiratory trouble. After Brutus and Doris came Echo. With a mournful roar, the playful spotted leopard fell sick and died. So did Reesha the Bengal tiger, a 15-year-old cat whom Colette had bottle-fed as a kitten.

Others survived. Like Tosh, the African lion rescued from playing guard dog at a San Bernardino junkyard. And Angela, the Bengal tiger abandoned by her circus trainers one winter day in a frozen Alaskan warehouse.

It is unclear whether the vaccine, or luck, saved the cats.

Day and night, staffers searched everywhere for the source of the virus. They tested pots and pans and animal feeders, examined mulch used to seed nearby oak trees, scraped paint on compound buildings. They studied soil, leaves and wood chips. One person was assigned solely to vector control, testing to see if the disease could be blamed on resident rats, mice, yellow jackets--even flies.

Each diseased cat was treated with antibiotics, anticonvulsants and tranquilizers to control its seizures. Heaters were installed because many suffered chills. At one time, 25 had fallen ill at once.

After every death, blood and tissue samples were ushered off to laboratories at Cornell and UC Davis as Yates and other staffers anxiously awaited faxes with news of any developments. They composed charts to map out where each sickened animal had been kept in the compound before falling ill. But no pattern emerged.

The disease attacked indiscriminately. Young and old. Male and female. One healthy animal would develop symptoms and survive for weeks. Another would be dead within the hour.

Each week, a new cat fell sick from the canine distemper virus--which attacks the respiratory, gastrointestinal, immune and central nervous systems. Some cats had all the symptoms, others one or two. In one arena, the disease killed three in a pride of seven lions, made two others ill and left the final two untouched.

“At times, you felt like those initial physicians treating AIDS patients,” Yates said. “It was so frustrating, not being able to slow or alter the course of the disease. Here was this crafty little virus that was fooling everyone.”

As the autumn dragged on, researchers concluded that the virus had been brought into the camp by a wild raccoon. Finally, in early January, Tibor the tiger became the last victim.

On a recent sunny weekday morning, Colette sighed as she walked among the lions, tigers and bears. “We have only questions,” she said. “No answers.”

Why, after countless centuries, did the canine distemper virus cross species? Was it some mutant or particularly virulent strain? Or, as some scientists suggest, did some other ailment such as the feline immunodeficiency virus weaken the cats’ immune systems, making them susceptible to the distemper virus?

Together, Cornell researchers and refuge staffers are logging data, continuing their search for the one clue that might finally solve their big cat conundrum.

All at once, as they grope through an uncharted medical jungle, it is Colette and her staff who feel caged.

“What was the common denominator to the felines who fell sick?” she asked. “We have to find out and stop it for good. The alternative is to lose every one of those beautiful animals. And that is just mind-boggling.”

Scientists also will ponder why the virus attacked only exotic felines at the refuge, leaving the domestic cats, such as mountain lions, untouched.

Meanwhile, the refuge remains on guard, and Yates is mistrustful of the future. Last week, staffers temporarily delayed lifting the quarantine after a leopard suddenly began coughing.

“You have nightmares of the disease once again rearing its ugly head,” she said. “And you know that none of those animals are really safe.”