(AP) NEW YORK A black Labrador who became a national canine hero after burrowing through white-hot, smoking debris in search of survivors at the World Trade Center site died Wednesday after a battle with cancer.

Owner Mary Flood had Jake put to sleep Wednesday after a last stroll through the fields and a dip in the creek near their home in Oakley, Utah. He was in too much pain at the end, shaking with a 105-degree fever as he lay on the lawn.

No one can say whether the dog would have gotten sick if he hadn't been exposed to the smoky air at ground zero, but cancer in dogs Jake's age — he was 12 — is quite common.

Some rescue dog owners who worked at the World Trade Center site claim their animals have died because of their work at ground zero. But scientists who have spent years studying the health of Sept. 11 search-and-rescue have found no sign of major illness in the animals.

The results of an autopsy on Jake's cancer-riddled body will be part of a University of Pennsylvania medical study of Sept. 11 search-and-rescue dogs.

Flood had adopted Jake as a 10-month-old disabled puppy — abandoned on a street with a broken leg and a dislocated hip.

"But against all odds he became a world-class rescue dog," said Flood, a member of Utah Task Force 1, one of eight federal search-and-rescue teams that desperately looked for human remains at ground zero.

Anguished New Yorkers honored the dogs.

On the evening of his team's arrival, Jake walked into a fancy Manhattan restaurant wearing his search-and-rescue vest and was promptly treated to a free steak dinner under a table.

Flood eventually trained Jake to become one of fewer than 200 U.S. government-certified rescue dogs — a muscular animal on 24-hour call to tackle disasters such as building collapses, earthquakes, hurricanes and avalanches.

After Hurricane Katrina, Flood and Jake drove 30 hours from Utah to Mississippi, where they searched through the rubble of flooded homes in search of survivors.

In recent years, Jake helped train younger dogs and their handlers across the country. Jake showed other dogs how to track scents, even in the snow, and how to look up if the scent was in a tree.

He also did therapy work with children at a Utah camp for burn victims and at senior homes and hospitals.

"He was a great morale booster wherever he went," says Flood. "He believed that his cup was always full, never half-full. He was always ready to work, eager to play — and a master at helping himself to any unattended food items."

Cynthia Otto of the University of Pennsylvania's School of Veterinary Medicine, who is researching the health of Sept. 11 dogs, expects Jake and the other animals being analyzed will serve as sentinels on possible long-term consequences stemming from 9/11.

Jake's ashes will be scattered "in places that were important to him," says Flood, like his Utah training grounds, the rivers and hills near home where he swam and roamed.