Pitbulls are widely used in dog fighting which is illegal across the US
By Nina Robinson
BBC News, Chicago
In Chicago, some of the city's most deprived neighbourhoods see more than their fair share of violence, with shootings an everyday occurrence.
Such areas are also home to a sub-culture of dog fighting, part of the estimated 40,000 people involved in the illegal activity across the US.
Tio Hardiman, from the the Humane Society of the United States's End Dogfighting Campaign, grew up in an inner city neighbourhood in Chicago.
He has first-hand knowledge of the street dog fighting culture in Chicago's South Side and West Side.
Mr Hardiman now works with former dog fighters, arranging training sessions for local pitbull owners to see dogs as loyal pets, rather than fighters.
'I would shoot my dogs'
One of the former dog fighters working on Mr Hardiman's campaign team is Sean Moore.
He admits that his actions during 13 years of dog fighting led to many animals being destroyed.
"Everything I did was bad," he says.
Some dogs have their ears cut off to encourage them to go for the neck
"Fighting them, preparing them to fight and once the fight was over, I killed them. I saw a lot of guys hang their dogs for hours and that's like torture. More often than not I would shoot my dogs, just to get it over with," he says.
Mr Moore also says it is not unusual for children to become involved from an early age.
He is mentoring a 14-year-old boy who has a tiger-stripe pitbull at his side.
The dog's ears have been cut off.
The practise of cutting ears is known as the "fight cut" and is done to encourage the dogs to go straight for the neck, rather than biting off the ears.
"Which more often than not," says Mr Moore, "will be bitten off anyway."
"I used to fight dogs in the back of buildings and abandoned garages. I went through almost 100 dogs, fighting them, just doing what I wanted to do with them, for no apparent reason," says the boy, who calls his current dog Tiger.
Tio Hardiman is trying to change the way people see pitbulls
He said he would find dogs in the neighbourhood and take them to fight.
If their subsequent injuries turned out to be too severe, he would leave them on the ground, the boy says.
Some dogs were picked up by the police, or he would tie a dog to a tree and walk away.
According to Mr Hardiman, there are three levels of progression in dog fighting.
Local children begin by staging dog fights on street corners to improve their standing in the community.
If their dogs emerge as winners, the children will appear tough and other people will be less likely to mess with them.
At the next level, money begins to change hands. "Anywhere between $500 and $2500," says Mr Hardiman, and the dogs are "trained to become ultimate fighters."
At the final, more professional level, dog fights are more organised and involve inter-state travel and dog fighting kennels, yielding earnings of up to $100,000.
Drugs, guns and sex
The fact that street dog fighting is happening in Chicago's poorest and most violent communities is no coincidence.
In a Chicago police survey of dog fighters, it was found that the vast majority of offenders had been arrested for other crimes, often involving drugs and violent assault.
Mike, an 18-year old juvenile offender from the South Side, went to his first dog fight aged just five.
He says dog fighting and other crimes are connected.
"Money, respect, power, showcasing the dogs' abilities, which dog has the bigger testicles, which has the bigger jaw - it's all about attributes of a dog, and money, drugs, guns and sex are involved in it too, because fighting dogs leads to selling drugs, selling guns and selling women," he says.
Some dogs have their teeth filed to make them sharper
Mr Hardiman agrees that many of the young men involved in the gang lifestyle and who put their dogs to fight become desensitised to violence.
Former dogfighter Sean Moore knows that growing up on the streets of a violent neighbourhood rmeans you have to show you are tough from a young age.
"A lot of us have got to be violent out here to even survive out here in these streets," he says.
"It's how we grow up and it's all we know. You'll see two humans fighting each other. If there's a shooting... we're going to run and see; we want to see who's going to get shot and who's doing the shooting."
Mr Moore admits that with daily murders and shootings, "Dog fighting right now, in the city of Chicago is the least of our problems."