The number of dangerous dogs used by criminals is soaring, sparking an epidemic of dog-related crime which has seen the number of animals seized by police nearly double in a year, and a three-fold increase in people needing hospital treatment for bites.
The explosion in popularity of so-called "weapon dogs", which are brutalised and trained by their owners to make them more vicious, has led animal welfare groups and politicans to call for urgent measures, including new laws, to tackle a phenomenon that threatens to overwhelm animal refuges.
The situation in some London boroughs is already "out of hand", The Independent has been told. Each month, dozens of animals – many of them maimed in fights with other dogs owned by gang members – are taken to Battersea Dogs Home and veterinary hospitals run by the RSPCA.
Scotland Yard said most of the dogs seized by officers were pitbull terriers – one of three breeds banned under the Dangerous Dogs Act 1991, which many critics say is failing to deal with the problem. Senior officers have seen a marked increase in dogs being used to attack or intimidate the public, or deployed in set-piece gang fights.
The Yard expects to seize more than 1,000 dangerous dogs this year, up from 719 in 2008 and an average of 45 a year between 2002 and 2006. In the past five years, hospital admissions for dog bites have risen by 43 per cent across the UK and by 79 per cent in London.
In a recent incident, police marksmen were called to a house in Tottenham, north London, after a pitbull-type dog clamped its jaws on to the arm of the owner's girlfriend. The dog was shot as a last resort. By then the woman, 23, was so badly mutilated that part of her arm had to be amputated.
The RSPCA said 60 per cent of the calls it received about dog-fighting concerned youths gathered with their pets in public places. Its inner-city animal hospitals deal with hundreds of injured "weapon dogs" each year, while Battersea Dogs Home said bull breeds now accounted for nearly 50 per cent of its "inmates", a proportion that had doubled in five years.
Concern about the proliferation of illegal breeds in deprived areas, where legal species such as the Staffordshire bull terrier are also seen by young gang members as status symbols, has led the Conservative Party to call for a new Dog Control Act to force owners to take responsibility for their pets.
The Deputy Mayor of London, Kit Malthouse, said consideration should also be given to banning all bull breeds which were inherently more aggressive than other dogs and were "canine weapons that terrorise the streets of Peckham, Toxteth and Moss Side".
Speaking after a meeting with police and the RSPCA, Mr Malthouse said: "There is a new weapon of intimidation terrorising the streets. Using a 'weapon dog' is no different to using a gun or a knife to attack, maim and even kill."
Over the past five years, a thriving black market in fearsome dogs, many of them bull breeds, has grown up in Britain's inner cities. Until 2008, the trade was extremely profitable with puppies selling for up to £500 apiece. There are now so many dogs available that the price has dropped to between £100 and £150 per puppy.
But experts say targeting particular species is counter-productive and will simply lead to unscrupulous owners turning other breeds into fighting dogs with brutalising techniques. These include beating and burning dogs to encourage them to fight, or teaching them to hang from tree branches to strengthen their jaws.
Claire Robinson, a spokesman for the RSPCA, said: "The breed-specific issue is a red herring. What we need is a fundamental overhaul of legislation to tackle the problem of irresponsible ownership.
"We need to be looking at measures such as tenancy agreements which can be used to ensure council properties are not used for indiscriminate breeding."
On the White City Estate, west London: 'She's not violent, she just likes to assert her authority'
Fabrizio Pezzolente, 22, and Pinka, 5
Pinka is "a bit of Labrador and a lot of pitbull", says her owner Mr Pezzolente, who is unemployed. "I don't think she's violent but when she is out in the park she likes to assert her authority. Sometimes I have to try to separate her from another dog. She is a dominant animal, that seems to be in her breeding. She likes to chase smaller animals. She is just a normal dog."
Alex Prior, 17, and Roxy, 1
Miss Prior took in Roxy as a puppy after the crossbred pitbull and Staffordshire bull terrier was abused by her former owner. "I know a lot of people who feed their dogs red meat to make them wilder. They burn or hit them to wind them up," said Ms Prior, a cloakroom attendant. "Staffies are loyal. Roxy will sit on your knee and fall asleep but they can turn quickly and be violent."
Margaret Doherty, 54, and Dexter, 2
"People who breed their dogs as weapons are horrible. They're normally crossbreeds," said Mrs Doherty, a housewife who has kept Staffordshire bull terriers for 35 years. Dexter is pure-bred. "I do not see any reason why we should not have a licensing system again. Staffs can get into mischief if you don't keep an eye on them. I only let him off the leash in the park."