TAMPA — A four-legged cancer patient named Shelby slipped away from a Tampa veterinary specialty center Wednesday morning, and her keepers have sent out an all-points bulletin hoping to find her.The 4-year-old Boxer mix was last seen near Dale Mabry Highway and Busch Boulevard, after escaping from a BluePearl Veterinary Partners hospital east of there, the hospital reported. She is brown and white and weighs about 40 pounds. "Shelby is one of our oncology patients," said spokeswoman Carrie O'Brion. "She's been receiving radiation treatments with us for several weeks."Blue Pearl is offering a $1,000 reward, she said, and about 20 hospital staff members have been searching the area. She has been spotted several times but has eluded capture."We're still looking into exactly what happened but at this point it appears that a kennel wasn't properly latched and she was large enough to push her way out the door," O'Brion said.Anyone who sees Shelby is asked to contact BluePearl immediately, either by emailing [email protected] or calling (813) 933-8944.