Dangerous dogs 'injected with steroids to increase their value for fighting and intimidation' Dogs are bred as 'business assets' for tough image Most aggressive dogs can be sold for more than £400 Dangerous dogs are being bred by young men as a business asset in drug deals, debt collection and for their gang image, according to research published today. More young men were using mastiffs, pit bulls, akitas and other aggressive dogs as a 'commodity' for security and making money in gangs, the study found. Dr Simon Harding, of Middlesex University London, who is behind the research, said: 'For many young people, dogs are increasingly viewed as a commodity which can be traded up or down like a mobile phone. The most aggressive dogs could be sold for more than £400, with owners building up their pet's muscles with vitamin supplements and even injecting them with steroids for fights It has become less about whether the dog will fit into family life and more about, "What will this dog do for me, how much will it make me?." He added 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. The study found the most aggressive dogs could be sold for more than £400, with owners building up their pet's muscles with vitamin supplements and even injecting them with steroids for fights. Dr Harding interviewed illegal and legal dog owners as well as gang members as part of his research. 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.' One 16-year-old boy said he would get about £2,000 for breeding a half-pit bull, half-mastiff dog Another boy, 17, said about pit bulls: 'People know that if you are breeding you are making money from them.' The study, which will be presented to the British Sociological Association annual conference today, also found there has been a rise of 551 per cent in hospital admissions for dog bites since 1991. Dr Harding said the growth in numbers raised the risk of attack, particularly for children. 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.'