The guard was not injured, because a wallet in his pocket protected him from the bite last week, according to a Palm Beach Gardens police incident report.
The incident occurred Friday night when the 5-year-old tan pit bull, Bambi, and a white Maltese toy dog were roaming around a guardhouse near Williams' home, the report said.
The guard traced the dogs back to Williams' home using a phone number listed on the Maltese's dog tag. Williams later told police the dogs got loose after she let them out and that she owned the Maltese but not the pit bull, the report said.
Williams told police she was watching the dog for a friend, the report said.
The dog is registered to Williams, Palm Beach County Animal Care and Control assistant director Dennis Yeskey told The Palm Beach Post. Animal control did not have records of Williams owning a Maltese, the AP reports.
Williams' Web site shows two photographs of a tan pit bull named Bambi. A spokeswoman for Williams declined to comment.
Telephone calls placed to Palm Beach County Animal Care and Control were not immediately returned Monday. A police spokeswoman would not comment on the case.