The days when anonymous cats roam the city of Pittsburgh with impunity may be numbered, if Councilman Jim Motznik gets his way.

Mr. Motznik plans to introduce legislation today extending the city's pet licensing requirement, which now applies only to dogs, to their sworn feline enemies.

Why? Two reasons.

"We're giving that animal more of a chance to be found by its owners," he said. A lost pet that's licensed can be easily reunited with its owners, and gets 10 days protection from euthanization, rather than the three days afforded unlicensed animals under the city code.

His other reason is based on personal experience.

"I have a fish pond. I chase cats out of my yard all the time," he said. "I want to have pet owners responsible for their pets, and right now cat owners are not responsible for their pets. There is a way of thinking ... that [cats] should be allowed to roam, and go on other people's properties, and I don't agree with that."

If a cat was getting into a neighbor's trash or otherwise damaging property, the owner could be more readily held responsible and fined if the cat were licensed, he said.

The proposal is getting mixed reactions from those who work with cats.

"In a perfect world, would I say cats should be licensed? Absolutely," said Gretchen Fieser, spokeswoman for the Humane Society of Western Pennsylvania. "The question is, who would enforce it?"

She said enforcement of cat licensing could require a change in state law, which treats dogs as the property of their owners, but is much looser regarding cats.

The issue last emerged in the city in 1992, when then-Councilman Jack Wagner, now the state auditor general, pushed a rewrite of animal policy that included cat licensing. Subjected to opposition and mockery, the provision was watered down to a requirement that owners of roaming cats put identification on their pets.

Municipal efforts to license cats have been relatively rare in recent years, said Joan Miller, legislative director for that New Jersey-based Cat Fanciers Association. "People who have cats consider it a tax," she said.

Mr. Motznik's bill would place the same annual fees on cats as now apply to dogs: $12 for animals that aren't spayed or neutered, and $7 for those that are.

"We're treating cat owners the same as dog owners," he said.

Dogs are different, the Cat Fanciers Association argues, because they are more likely to bite people or animals.

Licensing requirements can backfire by discouraging people from feeding, caring for, spaying or neutering, and eventually taking ownership of loosely owned or unowned cats, which make up 40 percent of the feline population in many areas, Ms. Miller said.

"Our effort is to get people to take responsibility for [roaming] cats," Ms. Miller said. "Cat licensing is a major deterrent to that."

Some communities have gone the other direction, she said, paying people around $5 for each roaming cat they bring in for spaying or neutering.

With the percentage of cats kept indoors growing, enforcement agencies "would have to go door-to-door" to achieve compliance, said CFA Executive Director Allene Tartaglia, and that "won't go over very well."

"The one argument you'll hear, that I'm prepared for, is that you can't put collars on cats," said Mr. Motznik. "There are procedures in place. In Canada, tattoos are placed inside a cat's ear. There are also procedures where a chip is put in place under a cat's skin."

The Animal Rescue League will place an identifying microchip under a cat's skin for $27.

The league's East Liberty shelter has long been the repository for stray or lost cats and dogs caught by the city's Animal Control Division. The league announced Friday that it would stop taking the division's strays after July 31, as a result of a spat with city officials over the proposed terms of a new contract.

Mr. Motznik's legislation doesn't specify the means of identification owners should use.

"Any way you choose, the cat needs to have some sort of identification," Mr. Motznik said. "I'm not going to choose for you."