The police dogs of Montgomery County will be among the first in the country to sport the latest rage in canine patrol wear: custom-fit bulletproof vests.

And, thanks to a generous donation from the Humane Society, they will never have to overheat again. The new "Hot Dog" sensors monitor when temperatures get too hot in parked patrol cars and automatically roll down the windows and kick on a fan.

The society contributed 21 vests, at $350 a pop, to the county's 17-member canine corps and to dogs belonging to Takoma Park police and the Montgomery County division of the Maryland park police. It also gave the county 17 temperature-monitoring devices that automatically roll down windows and start fans when parked patrol cars get too hot.

And for those inclined to snicker, canine officer Rupert Curry has this to say about his beloved partner, Rex: "All he has now when he goes after a suspect is his bite."

Montgomery County Executive Douglas M. Duncan (D), who was at the donation ceremony yesterday attended by the dogs and their handlers, said the new gear first struck him as a bit over the top.

"But then I talked to the officers," Duncan said. "They said it will make them more confident going into dangerous situations. It's psychological."

In the 40-year history of the county's canine department, only one dog, Blitz, has been shot and killed. In 1985, the police Rottweiler brought down an armed robbery suspect, who then stuck a handgun in Blitz's mouth and fired.

Sgt. Lee Marsh, commander of the county's canine corps, admits that a bulletproof vest would have made no difference for Blitz. Still, he eagerly draped Bandit, his German shepherd, in a new four-pound bulletproof vest. "You could make the argument that this is a luxury," he said. "But my life depends on how well he does his job."

Joseph F. Fernandez, vice president of Guardian Technologies International, the Virginia-based makers of the bulletproof canine vests, said Montgomery County's order was one of a spate brought on earlier this year when national TV shows featured Solo, a New Jersey police dog killed after a 23-hour standoff. The company used to make 50 or 60 canine vests a year, he said, now it makes about that many each month, with orders from canine departments from Florida to Oregon.

Indeed, the idea for the gift came as Sharon Kessler, executive director of the Montgomery County Humane Society, watched a news show about Solo on television. "I thought, this is absolutely too wonderful," she said.

In truth, very few police dogs are shot, according to the United States Police Canine Association. Some are run over. Others have been choked, beaten or drowned by suspects. One fell from a roof. Last year, eight dogs died in the line of duty.

"Usually, there are two or three a year who die," said Russ Hess, national director of the association. "And it's usually from heat exhaustion."

With that in mind, the Humane Society donated the "Hot Dog" temperature monitors. Now, when canine officers have to leave their dogs in the car, they raise the hood and leave the air conditioning on full blast. But just in case the car turns off, the Hot Dog device automatically blows the horn, turns on the lights or pages the officer while at the same time rolling down the windows and kicking on the Savvy Fan.

"It only takes five or six minutes at 90 degrees before these dogs will overheat," said Cpl. Scott McAuley, one of two Takoma Park police canine handlers to receive a vest, as he struggled to restrain his dog, Axel.

Janet Worsham, president of Criminalistics Inc. of Miami, which makes the Hot Dog monitors, is adamant that the Hot Dog is hardly an extravagance.

"A green dog, untrained, is worth $3,000 to $5,000. And after they're trained, as much as $17,000. That's quite an investment," she said. "Think how many years of service these dog give. And they're not drawing a salary or building up a pension."