They are meant to be man's best friend - a faithful furry companion in homes up and down the country.
But in recent years more and more dog owners have started trading their animals - particularly 'dangerous' breeds - as commodities for security and making money in gangs.
Now an academic study has revealed how dangerous 'status dogs' like akitas, pit bulls and mastiffs are being 'traded like mobile phones' and used as business assets in drug deals.
Some animals, having been trained to become stronger and more vicious, are sold for as much as £10,000, while puppies are bred illegally and sold to strangers for hundreds of pounds.
Dr Simon Harding, of Middlesex University, carried out research and found dealers selling legal and illegal cross-breeds for thousands of pounds at a time.
He was told by one 16-year-old boy: "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."
Another boy, 17, said about pit bulls: "People know that if you are breeding you are making money from them."
Dr Harding's research also found that a litter of six dogs can bring in £1,000, while prize pitbulls can fetch up to £10,000.
The study, which will be presented to the British Sociological Association annual conference today, also found there has been a rise of 551% in hospital admissions for dog bites since 1991.
The practice of selling illegal dog breeds for huge profit is not new.
Former Labour MP for Battersea, Martin Linton, said in 2010 that dangerous dogs bred illegally are sold to strangers in London pubs for £250.
Under the current Dangerous Dogs Act, owning a pitbull is illegal unless the owner has a certificate of exemption.
However, these certificates are rarely given out, and the dog has to be microchipped and neutered.
Previous investigations revealed how illegal breeds are often sold privately for hundreds of pounds - despite dealers admitting the animals are dangerous near children or other dogs.
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.
The issue remains at the forefront of the news due to high-profile dog attacks which happened recently.
Police said it is "unlikely" they will prosecute anybody over the death of a 14-year-old who was mauled by a pack of dogs.
Jade Anderson was discovered with wounds consistent with a dog attack at a property in Chaucer Grove, Atherton, near Wigan, on March 26.
She was visiting the house, the home of a friend, and was alone when she was attacked by four dogs - believed to be two bull mastiffs and two Staffordshire bull terriers - which were later shot by police marksmen.
Dr Harding added: "Dogs are what we make them, it is humans that are responsible for making dogs either sociable or aggressive."
In 2011, the Met Police seized 982 suspected illegal or potentially dangerous dogs - an average of more than 80 dogs each month.
They also initiated criminal proceedings against 153 people the same year.
A spokesperson for the Met told Yahoo! today: "The Metropolitan Police service works hard to tackle the problem of dangerous dogs. Where we receive information that a dog is 'dangerously out of control', we will investigate and take action.
"All dogs need to be properly managed, regardless of their breed, so they do not become aggressive and it is the responsibility of owners to keep their dogs under control."
The RSPCA have taken things a step further - they have contacted the Home Office to voice concerns over the dog control elements of the draft Anti-Social Behaviour Bill.
Ministers have been accused of 'watering down' dog control laws with plans to replace them with general 'public spaces protection orders'.
An RSPCA spokesperson said today: "Having a dog is not a right; it is a privilege. With that privilege goes responsibility to provide for that animal’s welfare needs and to raise it properly."