Rise in thefts of black cocker spaniels as price goes up because of Kate and William's dog Lupo Royal couple got cocker spaniel Lupo in December 2011 The breed's popularity then skyrocketed But this has lead to spate of thefts of dogs who resemble Lupo Pet Detectives agency says it is investigating more cases than ever The Duke and Duchess of Cambridge have always been trend-setters, even more so since the birth of Prince George. But one phenomenon they might not be pleased to be associated with is a recent spate of dog thefts. Thefts of stolen black cocker spaniels, which resemble the couple's dog Lupo, have reportedly increased dramatically since the newest Royal canine was thrust into the spotlight. Trend-setter: Lupo, right, was adopted by William and Kate, and featured prominently in this family portrait, showing newborn Prince George A professional pet detective has said he is investigating a record number of stolen Lupo lookalikes, which he suspects have been taken by criminal gangs looking to cash in on the breed's popularity. We are currently looking for 13 and have recovered five in the past 12 months,' Colin Butcher, director of the Pet Detectives agency, told the Daily Telegraph. 'They are the tip of the iceberg, as a lot of people probably don't realise that their dog has been stolen. Many may think they have been run over or just gone astray. It is not travellers or thieves that are for the most part responsible, but organised gangs who have people who want these dogs. Royal's best friend: Lupo is often seen out and about with the Duke and Duchess of Cambridge Although demand for particular breeds of dog can fluctuate drastically according to the fashion of the day, respectable breeders often do not wish to meet the new demand, which can lead to people trying to acquire the dogs illegally. Figures released in January this year suggested that the number of reported dog thefts had rocketed by 17 per cent to more than 3,500 a year. The biggest increase was said to be in black cocker spaniels after it was revealed that William and Kate adopted Lupo in December 2011, which can now sell for up to £1,000. In April this year a black cocker spaniel which looked just like Lupo was stolen from a farm in Surrey. Jodie Ferrier, who bought lookalike Fern for the three-year-old son, is convinced a breeder snatched her dog so she could produce more puppies. Police investigated the theft of the dog, which was microchipped, but were unable to find the animal. The Kennel Club, which vets dog breeders in the UK, said that general interest in cocker spaniel puppies had increased 9 per cent since Lupo was introduced to the world, while the number of puppies being born each year - around 23,000 - had remained the same. Since he joined the family, Lupo - whose name was kept secret until he was three months old - has been a regular fixture of Royal life, and appeared prominently in the first official photograph of newborn Prince George. Kate was often spotted walking Lupo around Angelsey, where she lived while William was serving as an RAF search-and-rescue pilot until earlier this month. The duchess - whom a friend said was 'besotted' by Lupo - received the dog as an early Christmas present from her parents after he was bred from their family pet.