KANSAS CITY, Mo. — For much of the past three decades, pit bulls have been widely regarded as America’s most dangerous dog — the favorite breed of thugs, drug dealers, and dog-fighting rings, with a fearsome reputation for unprovoked, sometimes deadly attacks.
Hostility toward ‘‘pits’’ grew so intense that some cities began treating them as the canine equivalent of assault rifles and prohibited residents from owning them.
But attitudes have softened considerably since then as animal activists and even television shows cast the dogs in a more positive light. The image makeover has prompted many states to pass new laws that forbid communities from banning specific breeds. And it illustrates the power and persistence of groups that have worked to fend off pit bull restrictions with much the same zeal as gun-rights groups have defeated gun-control measures.
‘‘Lawmakers are realizing that targeting dogs based on their breed or what they look like is not a solution to dealing with dangerous dogs,’’ said Lisa Peters, a spokeswoman for the American Kennel Club.
Seventeen states now have laws that prohibit communities from adopting breed-specific bans. Lawmakers in six more states are considering similar measures, and some cities are reviewing local policies that classify pit bulls as dangerous animals.
Pit bull advocates hail the changes as recognition that breed-specific laws discriminate against dogs that are not inherently aggressive or dangerous unless they are made to be that way by irresponsible owners.
The dogs’ foes complain that their message is being drowned out by a well-funded, well-organized lobbying effort in state capitols. The debate puts millions of pit bull owners up against a relatively small number of people who have been victimized by the dogs.
Ron Hicks, who sponsored a bill in the Missouri House to forbid breed-specific legislation, said he was surprised when nobody spoke against his proposal last month at a committee hearing.
‘‘I figured a few parents would be there who would bring tears to my eyes,’’ the Republican said. ‘‘Would it have changed my opinion or what I believe in? No.’’