Though illegal in all states and a felony in 47, dogfighting is on the rise, particularly outside its traditional stronghold in the Deep South.

Lawmakers and humane officials are seeking new ways to attack the trend, however, and investigators see a "gold mine" in a list of thousands of potential suspects seized in a recent bust, along with scarred dogs, steroids and canine treadmills.

More than 100 Web sites sell pit bull training gear. About a dozen dogfighting magazines publish regularly, up from three in the 1980s. The FBI keeps no statistics on the activity, but authorities estimate -- from breeders' advertisements, magazine subscription lists and previous arrests -- that at least 40,000 people in the United States breed or own pit bulls for fighting.

"It's definitely on the upswing. Communication on the Internet has made dogfighting accessible without the inherent risks of arrest that used to go along with it," said Mark Kumpf, a Virginia investigator with the National Illegal Animal Fighting Task Force, made up of U.S. Department of Agriculture officers and local police nationwide.

In cities, owners fight their animals on street corners and alleys. In rural areas, organized fights have strict rules -- and wagers between $100 and $50,000. The winning dogfights another day. The loser may be nursed back to health, if valuable, or it may be shot or abandoned.

Investigators say there are at least 50 breeders in the United States who have farms with hundreds of the dogs. A 36-year-old Oklahoma man who breeds pit bulls for fights, speaking on condition of anonymity, said he grew up among people involved in dogfighting and has seen more and more get involved over the past decade.

"Nobody can stop it," he boasted.

A videotape confiscated from a recent New Orleans arrest shows a training fight between a mature pit bull, Kay, and a dog that appears to be a year old. Men held the dogs apart on soiled carpet inside a square "fight pit" enclosed by wooden planks.

Once they were released, the snarling dogs attacked each other. Their owner cheered as Kay chomped down on the muzzle of the younger dog, whipping its head back and forth for nearly 10 minutes.

The owner argued with another man over whether to stop the fight to protect the younger dog, which had started whimpering.

"I think you should pick her up and save her."

"I don't do that. If she can stand, she can fight," the owner replied.

The fight continued, and the young dog was pinned on its back; finally it stopped resisting. Men pried the animals apart.

The young dog stood panting, staring straight ahead. "She's had enough," a voice said. "She's in shock."

The American pit bull terrier emerged as the preferred fighter after more than a century of breeding for strength, agility and jaw power. Champion fight dogs also have what owners call "gameness" -- an eagerness to attack despite ripped flesh, dehydration, exhaustion or broken bones.

Owners express deep pride in their dogs' abilities, comparing the animals to professional athletes. In a Web posting, one recalled his pit bull's recent victory as "the most fulfilling moment of my life."

Most of a fighting dog's life is spent with a heavy chain around its neck, according to breeders who say restraints are necessary to keep the animals from escaping and injuring other animals.

The dog runs for as much as an hour at a time -- sometimes several times a day -- on a treadmill. Its jaws are strengthened with "springpoles," hung from trees with a lure attached. The dog clamps its jaws on the lure and whips its head back and forth, perfecting the "bite and shake" technique.

Organized dogfighters often liken themselves to horse breeders: They say they treat their animals well and breed champions with champions. Many learned to train from their fathers and grandfathers.

It is unfair, they say, that dogfighting is illegal while activities in which humans kill animals -- fishing and hunting -- are condoned.

On Internet sites, they have answers for those who call dogfighting cruel:

* Injured dogs quickly receive medical care. A champion can be worth $10,000, and it would be foolish to withhold treatment. (But animal welfare officials say wounded dogs typically receive shoddy medical care -- including sutures and intravenous drugs -- from owners who are not veterinarians.)

* A fight is halted when one dog stops attacking, thus minimizing injuries. (Humane Society officials respond that fights inflict terrible pain on dogs, no matter what fight rules are followed.)

* Pit bulls were bred to fight, just as retrievers were bred to fetch. The animals enjoy fighting; look at their tails wag. (Animal welfare officials say the animals appear to enjoy fighting only because breeding programs heighten aggressiveness. That also means that most fight dogs that are seized are unsafe for adoption and must be euthanized.)

"Cruelty is in the eye of the beholder," someone posted on a pit-bull-related Web site in response to a query.

In the eyes of officials of the Humane Society of the United States, any form of dogfighting is a vicious blood sport.

Investigators are going after the clandestine sport, and they staged a number of raids in 2003.

Among them:

* In Petaluma, Calif., a man was arrested after police searched his property and found 15 pit bulls and a bloody treadmill.

* In Orangeburg, S.C., 70 pit bulls were confiscated from an alleged fighting ring.

* Near Erie, Pa., authorities made 11 dogfighting arrests and seized 32 pit bulls.

The district attorney's office in Pittsburgh had its first-ever dogfighting case five years ago, and has prosecuted 24 people for dogfighting since then.

On pit-bull-related Internet message boards, anonymous postings now warn dogfighters that the Pittsburgh area should be considered off-limits because the risk of raids and arrests is too great.

Earlier this month police raided a rural house in Covington, Ga., and arrested 123 people on dogfighting and gambling charges. In the house they found a blood-soaked dogfight arena where fans had gathered for a night of gambling with a winner-take-all pot of $50,000. Deputies seized about a dozen guns, several kilograms of marijuana and cocaine and more than a quarter of a million dollars. One pit bull was dead, another dying and 13 were placed in the care of county animal control officers.

A bill pending in Congress would make it a felony to transport fighting dogs across state lines. The Humane Society considers the bill an important effort to disrupt what is considered a nationwide dogfighting circuit.

"If the locals can work with the federal government to catch them, that will give them another tool," said Sen. John Ensign (R-Nev.), a sponsor.

A key arrest came in April, when Orange County, N.Y., police charged former bodybuilder James Fricchione, 33, with felony dogfighting and identified him as publisher of the Sporting Dog Journal, a leading dogfighting magazine.

The magazine had been published six times a year on cheap paper, featuring fight results and advertisements for pit bull breeders, most with the disclaimer: "Not Intended For Any Illegal Purposes."

The magazine never printed its address. To deter undercover police, subscriptions were sold only to people who had references from other subscribers.

Investigators said Fricchione's arrest came after several years of investigations into the national dogfighting circuit. On the day he was arrested, police in Georgia also raided and seized records from the Georgia home of Jack Kelly, Sporting Dog Journal's former publisher.

At Fricchione's home, investigators found canine treadmills and 18 pit bulls -- many of them scarred, one with a fractured jaw -- and steroids that investigators believe he fed to the dogs.

Fricchione pleaded not guilty to 33 charges of animal cruelty, dogfighting and promoting dogfighting. If convicted of all charges, he faces as much as 12 years in prison.

Norman Shapiro, Fricchione's lawyer, said his client is a breeder who has nothing to do with dogfighting. Messages left at Fricchione's home were not returned, but in the July-August issue he printed this statement:

"As dogpeople we should take heed and make changes to insure our safety. Remember, the Humane Society has been raiding people's homes since the '70s and will continue their witch hunt for as long as the [pit bull] remains in existence."

For investigators, Fricchione's arrest had a special dividend. They seized his list of more than 5,000 Sporting Dog Journal subscribers -- all of whom are suspected to be involved in dogfighting, according to a law enforcement source, who predicted further arrests.

Kumpf, the Virginia investigator, called the list "a gold mine."

"A lot of us out here in law enforcement are waiting for the gold rush to hit."

All of the dogs taken during the New Orleans raid in October were euthanized because they had been trained to fight and attack other dogs.A pit bull puppy waits in a truck after animal officers found 13 dogs chained to trees, a fence and abandoned cars in New Orleans last fall. Mark Kumpf, a Virginia investigator with the National Illegal Animal Fighting Task Force, stands in the Norfolk Animal Protection Unit's "pit bull alley."