An 80-year-old Alameda woman died three days after she was bitten in the hand by a dog, authorities said Thursday.

Dolly Newell was walking her Rottweiler, named Lily, at about 1 p.m. Saturday on Bay Farm Island when another dog bit her finger, police Sgt. Don Owyang said.

Newell didn't report the bite because she didn't want the dog to be quarantined, investigators said. Instead, she told doctors at Alameda Hospital that she had injured herself while gardening.

A couple of days later, a friend went to check on her and found her semi-conscious.

She was taken back to the hospital, where she died Tuesday of an infection from the bite.

Newell had told acquaintances the real cause of her wound. Now police are trying to find the dog.

Anyone with information is asked to call police at (510) 337-8319.