A pioneering police unit aimed at taking the most dangerous dogs off the streets has seized more than 1,000 animals in its first year.
The Metropolitan Police's status dog unit was formed to tackle the growing problem of violent animals in the capital.
The team, made up of a sergeant, five constables and civilian worker, is responsible for targeting those who breed, sell and fight dogs.
They are supported by a senior RSPCA officer who uses his expertise and enforcement powers to ensure dogs are kept in the right conditions.
Since its launch on March 2 last year, staff have seized more than 1,070 dogs, including 900 pit bulls.
They have witnessed an explosion in the breeding of potentially dangerous dogs, with many people crossing pit bulls with other breeds to get around the law.
Puppies can sell for £300 to £400 each, but the extra supply has seen the bottom fall out of the market in some areas and many unwanted animals.
Investigators believe many gang members are training dogs because high-profile stop-and-search tactics have forced them to give up knives and guns.
As a result the status dog unit has given priority to many of the inner London boroughs most affected by knife crime.
Young men also fight dogs for entertainment, sometimes filming their exploits on mobile phones and posting them on the internet.
One raid in Ealing, west London, sparked by reports of a gang member breaking the legs of puppies, led to the recovery of two pit bull-type dogs.
Further inquiries brought officers to the door of two other gang members who were arrested when 500 grammes of heroin was found.
The status dog unit has led training for regional police forces, supported by the Association of Chief Police Officers (Acpo).
Last month a policeman was savaged by two pit bulls in Plumstead, south-east London, as he attempted to arrest a man on suspicion of not paying court fines.
John-Jo Madden, 18, whose pitbull attacked a guide dog at Cricklewood station in north London, was banned from keeping dogs for 10 years.
A Metropolitan Police spokesman said the force is working hard to tackle dangerous dogs.
He said: "A growing trend to own so-called status dogs has led to an increase in people acquiring illegal dogs and dogs being used in gang-related crime, drug dealing and anti-social behaviour. This has led to us setting up a dedicated unit to deal with the problem.
"Since its launch in March 2009, the status dogs unit has seized over 1,000 dogs. Dealing with dangerous or status dogs is not just a problem for the police however, and the Met does not work in isolation.
"We work closely with local councils and animal welfare agencies, including the RSPCA among others, to tackle the problem.
"An example of this work is BARK, a partnership between police, local councils, the RSPCA and other animal welfare officers, which aims to educate people about responsible dog ownership.
"The team visit houses in the area making sure owners are properly looking after their pets and provide free microchipping."