Dangerous dogs are being “traded like mobile phones” and used as business assets in drug deals, according to research.
Young men are breeding the dogs, injecting them with steroids and vitamin supplements and filing their teeth to make them more aggressive before selling them, sometimes for up to £10,000.
Gang members are using so-called “status dogs”, such as pit bulls, akitas and mastiffs, as a “commodity” for security and making money in gangs, the study concluded.
Dr Simon Harding of Middlesex University, London, carried out the research.
He told Sky News: “What I found that really surprised me was that dogs were being used in an entrepreneurial way.
“They are being used to make money so they are being seen as a commodity, less than for example a sentient family being but more in terms of what can this dog do for me? How much can this dog make for me?”
He said that “through their reputation for aggression or ability to intimidate”, bull breeds “are also used in drug deals, gambling debts and loan-sharking, where their owners do not have recourse to law if the money owed is not paid because his business is illegal.
“The dog says, ‘I am here to be taken seriously’ – it acts as a ‘minder’ and a ‘heavy’ when collecting dues. People believe that possession of an aggressive dog means that the threats posed by such men will be carried out.”
Dr Harding interviewed illegal and legal dog owners as well as gang members as part of his research, often being threatened by those he spoke to.
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.”
Dr Harding’s three-year research found that some animals could sell for up to £10,000.
The owner of the dogs that attacked and killed the 14-year-old Manchester girl Jade Anderson bred pups at her terraced home and sold them on eBay. However, none of the dogs were illegal and there are to be no charges.
Under the Dangerous Dogs Act 1991 only the pit bull terrier, Japanese tosa, dogo argentino and fila braziliero are banned.
However, many breeders will cross the dogs with other animals in an attempt to hide their breed.
The study, which will be presented to the British Sociological Association annual conference later, also found there has been a rise of 551% in hospital admissions for dog bites since 1991.
Dr Harding said the growth in numbers raised the risk of attack, particularly for children.
He said that of the many parks he had visited in south, west and east London, at 85%, he found “status” or “weapon” dogs were present.
He called for animal welfare agencies and the police to work more closely to tackle the issue.
Dr Harding added: “Dogs are what we make them, it is humans that are responsible for making dogs either sociable or aggressive.”