The Santa Rosa Press Democrat reports the public has donated more than $7,000 for Bosco's care.
He spent his career with the Rohnert Park Police Department.
Bosco was diagnosed last month with an aggressive form of bone cancer and had his right leg and shoulder amputated. He underwent his first chemotherapy treatment this week.
His treatment is expected to cost $9,000.
Cover Your Retired K-9, a nonprofit that provides aid to police dog handlers as well as emergency care for retired dogs, set up a fundraising link called "Go To Bat For Bosco."