Duffey knew the dead dogs found in the county's rural areas weren't strays, because the pads of their feet and their nails had not been worn down from a life on the streets. So Duffey checked the lost-and-stolen-animal reports kept by the local humane society.

"We found that a lot of the dogs found in these desert dumping areas were in fact, at one time, [reported] stolen," said Duffey, co-chair of the Animal Cruelty Taskforce of Southern Arizona, an organization made up of law-enforcement, criminal-justice, and animal-protection professionals. "So we began looking for a connection."

That connection was made when the veteran detective found a copy of the American Patriot. The journal, he said, was filled with pictures of fighting pit bulls kept in the very same areas where officers were finding the remains of mauled dogs.

Duffey says a large number of animals are reported lost in Pima County. Within the last six months, 3,396 animals have been reported missing. Of that amount, Duffey estimates 50 percent may have been stolen.

"Animal control has enough people out on patrol, so if [an animal] was truly a stray, they'd encounter it," Duffey said. "But they never turn up as strays; they just turn up as missing. Then somewhere down the line, we find one in the desert that matches the description of four or five that were reported stolen."

In January the sheriff's department began to tally local pets stolen by dog-fighting operations. Officers match the descriptions of animals found dumped in the desert to those reported missing.

National statistics on how many pets are taken each year and used as bait by dog-fighting rings are not available.

"I think every state has a problem with it, whether they know it or not," said Patricia Wagner, head of the National Illegal Animal Fighting Task Force for the Humane Society of the United States.

Wagner said news reports about stolen pets in the U.S. have appeared in California, Colorado, Florida, Illinois, New York, North Carolina, Ohio, and Texas, among other states.

To protect pets from being stolen, owners should care for their animals like they would a four-year-old child says Marsh Myers, director of education and community outreach for the Humane Society of Southern Arizona in Tucson. Both children and pets, he says, have similar levels of curiosity and vulnerability.

"Pet owners need to play that role of parent," Myers said. "We live in a society that has some dangerous people in it, and they will target your pets if they're allowed to."

Small dogs, kittens, and rabbits are more at risk of being stolen for bait, experts say. Pit bulls, though, are commonly targeted by dog fighting rings for potential breeding stock.

In Arizona state representative Ted Downing introduced a bill last month that would make stealing an animal for use in dog fighting a felony with penalties up to two years in jail and fines as high as U.S. $150,000. If the bill becomes state law, Downing says, it could be the first of its kind in the country.

Cruel Contest

Dog fighting is illegal in all 50 states and a felony in 47. Still, law-enforcement officials and animal-care professionals say they've seen a recent increase in the blood sport.

"There's so much of it going on [nationally]," said detective Mike Vadnal, who for 12 years has investigated animal crimes for the Broward Sheriff's Office in Broward County, Florida. "It's out of control."

Last April the alleged publisher of Sporting Dog Journal, which is thought to be the largest underground magazine for the dog-fighting industry, was arrested in New York, according to Vadnal.

Vadnal said the last printed edition of the magazine listed about a thousand fight reports. The fights were by "professionals" who breed and fight animals throughout the country for profit, Vadnal said. There are also other, less organized groups who spar their dogs for bragging rights and quick cash.

In such contests, according to law-enforcement officials, two dogs are placed in a pit or similar area enclosed with plywood walls. They attack each other while crowds of up to 200 people watch and cheer. Bets ranging from U.S. $10,000 to $50,000 are made on fights.

The bloody battle often lasts two hours or more, ending when one dog is no longer able to continue. The breed most often used is the American pit bull terrier. Experts say dogs that survive often die hours, sometimes even days, after the fight—usually of blood loss, shock, or infection.

The practice has been linked to other crimes. In Arizona, for example, Duffey said spectators and dogfight operators are often involved in auto theft, drug dealing, arms smuggling, and money laundering.

The Humane Society of the United States keeps a database of news reports on dog fighting. It estimates 40,000 people are involved in the blood sport and 250,000 pit bulls are used.

The Internet has helped fuel dog fighting by making it easier for criminals to communicate, says Wagner of the Humane Society. At last count there were about 500 message boards and chat rooms devoted to dog fighting, and the number keeps growing, Wagner said.

As dog fighting proliferates, the number of stolen pets has also grown. Whether the two are directly linked is unclear.

Sandy Christiansen, a program coordinator for the Tallahassee, Florida-based Humane Society of the United States, says his office receive reports almost daily from animal shelters around the country about neighborhood pets being nabbed.

But Christiansen, a former animal control investigator in Rochester, New York, says teenagers, not professional dog fighters, may be to blame.

"My experience mostly has been in an urban environment where the dogs that are being stolen are often used by less sophisticated people who are looking for the thrill of watching their dog beat up another dog," Christiansen says.

A Humane Alternative

Concerned by the increasing number of youths involved in dog fighting, former animal control officer Sue Sternberg decide to do something about it.

In 2002, Sternberg started Lug-Nuts, a program that encourages inner-city teens to enter their dogs in weight-pulling contests instead of fights.

"Weight pulling is a very macho sport, and it's incredibly humane," said Sternberg, who now runs a boarding, training, and adoption kennel called Rondout Valley Animals for Adoption in northern New York State.

Owners encourage their pets—harnessed to plastic sleds filled with dog-food bags—to move forward with words of encouragement and tasty treats.

Monthly contests are held in Harlem's Marcus Garvey Park, drawing about 15 entries and a large crowd of onlookers, Sternberg said. Winners receive cash prizes and pet supplies.

Sternberg said the program also encourages owners to neuter and spay their animals and offers to pay for the surgical procedure.

Shelters in the Northeastern U.S. are filled with dangerous dogs, Sternberg said, because teenagers involved in dog fighting are breeding their animals every six months for profit. Some teens are making between U.S. $1,500 and $2,000 each year selling puppies.

Consequently, shelters are filling with pit bulls and pit bull mixes that are not adoptable, because they've been trained to be aggressive toward other animals and sometimes humans.

Sternberg is currently working on a Lug-Nuts training manual and video for animal-care professionals interested in starting the program in their areas. newsdesk@nationalgeographic.com