"It's a fallacy that one breed is more dangerous than another," he said. "Everyone has prejudices ... but the willingness to bite is probably the same, on average, in a bichon frise as in a Great Dane."
Mugford recommends that owners take action as soon as they spot any warning signs -- by going to a dog trainer or qualified behaviorist, asking a veterinarian for advice or investing in a muzzle.
"If you have a big dog, or several big dogs, it's pretty obvious that you must take it very seriously indeed," he said. "Assume that the worst can or might happen."
The laws in Britain are sufficient to protect people if they are enforced, he said. "But more than anything, we need common sense -- punishment after the act is not the solution, we need behavior that anticipates problems."
Pit bull issue
The debate over dangerous dogs is also heated in the United States, where the Humane Society has been campaigning against a Maryland Court of Appeals ruling in August that pit bull terriers are "inherently dangerous."
Under the ruling, dog owners and their landlords are responsible for any injuries caused by pit bulls.
The Humane Society says it's wrong to discriminate by breed.
"Singling out a particular breed or type of dog has repeatedly been proven to be ineffective at curbing dog bites because breed alone is not predictive of whether a dog may pose a danger," its website says.
"A dog's propensity to bite is a product of several factors primarily under the owner's control, including early socialization, whether the dog is spayed or neutered and whether the dog is isolated or chained."