After tobacco, alcohol, and sports utility vehicles, how long will it be before public health experts get serious about the menace of widespread dog ownership? Despite ongoing research into dog bites and zoonoses, the occasional media outcry about pit bull terrier and rottweiler maulings, and legislation such as the United Kingdom's Dangerous Dogs Act of 1991, pet dogs and their owners have mostly been given a rather long leash. And yet it increasingly seems extraordinary to me—considering all the things that the law prevents us from doing—that it is legal for people to keep a potentially dangerous wild animal in their home. Or even, as many postmen and postwomen have discovered to their cost, in their front gardens.

In 2003 the UK had about 6.5 million dogs, estimates the Pet Food Manufacturers' Association (www.pfma.com/public/petownership_stats.htm), although the abolition of the dog licence under Mrs Thatcher's government in 1987 has hampered the collection of data on ownership. That is roughly one dog for every 10 people. (A crude survey among my BMJ colleagues found that, of 35 who replied to an email question, seven were dog owners, double the proportion in the country as a whole.) The only requirement by law in England and Wales is that dogs must wear a collar in public bearing its owner's name and address, although bylaws …