Dr Simon Harding, of Middlesex University London, interviewed illegal and legal dog owners as well as gang members as part of his research.
The research found that dangerous dogs are being bred by young men as a business asset in drug deals, debt collection and for their gang image.
A 16-year-old boy told him: "It's not just a dog, it's a half bull mastiff and half pit bull. I'll probably get another - we are looking to breed it - and we would get about £2,000 per dog."
Another boy, 17, said about pit bulls: "People know that if you are breeding you are making money from them."
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A humid night for some with thundery downpours in places.
The 20-year-old was found fatally wounded on Roth Walk, near Finsbury Park, north London at around 3am on Saturday, Scotland Yard said.
Daniel Cowell has been jailed for five years and four months after ramming a police patrol car with a stolen transit van.