But they plugged it up, she said, most likely because they included some cat litter and because it's a low-flow toilet.

She said she can't bury it because of an excess of roots from trees in the backyard, so she throws it in the garbage and has never gotten a $25 ticket.

"I wouldn't mind if they would tell us a good way to dispose of their waste that would work," she said. "I'm not spending my time researching what to do with cat poop."

Cat licensing, containment

Cats also are supposed to have city licenses, but only 1,582 licenses were applied for in 2009, according to the city clerk's office.

If, as the U.S. Humane Society estimates, 33 percent of American households have at least one cat, that could mean there are at least 28,000 contraband cats prowling around the city.

Cats that leave their owner's property also are required to be on a leash, but free-roaming cats are rarely caught when reported.

"By the time they call it in and when they get there, it's usually gone," said Patrick Comfert, animal services lead worker for Public Health Madison and Dane County.