The little dog named Bear was first diagnosed with the disease in November 2010, and at the time it was believed he would live only six to nine months, the (Munster, Ind..) Northwest Indiana Times reported.
But Bear wasn't ready to go and his owners, Lisa and Tim Kappert of Mascoutah, Ill., were more than willing to help him stay, the newspaper said.
Lisa Kappert told the Times Bear is still playing with his toys and eager to go to the park every day. "He loves life, and he keeps going," she said.
Bear, who is a special patient at the University of Illinois College of Veterinary Medicine, is still considered terminally ill. But he has amazed his caregivers, the Times said.
Dr. Joanna Schmidt, the oncology resident overseeing his care, said, "I think he has nine lives." Though rare, prostate cancer in dogs can be treated but never cured, the newspaper said.
Bear underwent traditional chemotherapy, non-traditional chemotherapy and radiation. Then Dr. Heidi Phillips, who had just joined the UI staff, removed Bear's right kidney, which had been destroyed by the tumor.
To keep his left kidney functioning, she relocated his ureter to the forward part of the bladder, and then inserted a tube that the Kapperts need to help him during his final days.
Phillips says Bear may only have several more months ahead, "But the good news is, it's good quality time. And for the owners, that was worth it. They weren't ready to say goodbye."