Criminals could be targeting Staffordshire Bull Terriers for theft, according to a report released under the Freedom of Information Act.
The Metropolitan Police document shows a 74% rise in stolen dogs across the London area last year.
The report, obtained by the BBC under the FoI Act, says Staffordshire Bull Terriers made up more than half of all dogs stolen, with nearly 35 being taken a month, many as puppies.
A total of 417 dogs were stolen in the financial year 2005/06, compared to just 228 in the financial year 2003/04.
The worst areas for the thefts in London have been Croydon, Bromley, Greenwich, Haringey, Lambeth and Hackney.
The report says some criminals may be using the dogs to guard "criminal assets".
It goes on to recommend further research into why Staffordshire Bull Terriers are so heavily targeted.
The report states: "There is the possibility that such dogs could be used by criminals such as drug dealers or stolen property handlers to protect their criminal assets at various locations including homes, outbuildings or cars."
The police document notes that thefts of dogs from people's homes seems to occur when they have advertised dogs, particularly puppies, for sale. This can often result in several dogs being stolen at once.
