Malarie Stafford, 3, plays with Poseidon, a 9-year-old pit bull, in Aurora on Wednesday. City leaders will consider a ban on pit bulls Aug. 9, while Commerce City could outlaw them tonight. Denver banned them in 1989. (Post / Will Singleton)

Aurora - Peter Mustacchio looked on as his 3-year-old granddaughter tossed a tennis ball to Poseidon - Mustacchio's 9-year-old pit bull.

The girl was about the same height as the dog, whose massive jaws quickly clamped down on the ball before it scampered into the backyard.

It was a scene that would make pit bull critics shiver.

This, after all, is the type of dog some call an unpredictable killer, the preferred hound of drug dealers, with a bloodline filled with violence.

Pit bulls also are family pets, loved by thousands of Americans.

Pete, the amiable pooch with the circle around his eye in "Our Gang," was a pit bull. So was Buster Brown's trusty hound, Tige.

Nevertheless, pit bulls are no longer allowed in Denver, Castle Rock, Wiggins, Wellington and Fort Lupton.

Aurora leaders will explore a ban in an Aug. 9 meeting, and Commerce City may approve one tonight.

The debate over pit bulls continues to swell across the country as other cities consider similar restrictions.

"It's a shame," Mustacchio said, smiling as his granddaughter, Malarie, played with his dog. "They don't get much better than Poseidon. He's never been aggressive. It's not the breed. It's the owner."

The debate of whether a pit bull is a killer or a potential best friend touches deeply on both sides of the issue.

Lines are clearly drawn. Each side has facts, studies and arguments about the dogs.

"This is coming from unnamed fear," said Sonya Dias, a Denver resident and pit bull owner who is organizing rallies against the ban. "You're not going to hear about a dog bite unless it's a pit bull."

In contrast, city leaders in Denver and Aurora note that pit bulls have been bred through the centuries to be vicious.

They cite dozens of attacks that killed or maimed people and say banning the dogs will protect the public.

"For every little Muffy that is as cozy as a bedroom slipper, there is a killer," Aurora Councilwoman Molly Markert said.

Technically, a pit bull is not a breed. It's a generic term, like "retriever," that describes an American pit bull terrier, an American Staffordshire terrier or a Staffordshire bull terrier.

A federal Centers for Disease Control and Prevention study found that at least 25 dog breeds were involved in 238 fatalities from 1979 to 1998. Pit bull-types and Rottweilers accounted for 66 and 39 deaths, respectively.

The CDC study warned against specific bans, saying breeds responsible for attacks vary over time. Great Danes, for example, were the lead killers from 1997 to 1998, and other breeds have killed as well, including Dachshunds, a Yorkshire terrier and even the popular Labrador retriever.

Approximately 4.3 million people are bitten every year, and about 800,000 of those incidents require hospitalization. No group has done an analysis of which type of dog bites more.

Organizations such as the Humane Society of the United States and the American Veterinary Medical Association oppose breed-specific bans. They say one of the biggest problems is determining the breed.

The best way is through DNA analysis, which is expensive and time consuming. Denver uses a visual checklist, looking at the structure of the dog's head, body and coat.

"Using breeds as the only indicator that a dog is going to be a danger is a bad idea," said Stephanie Shain, director of outreach for companion animals for the Humane Society of the United States. "You get rid of