Scott Seymour said his dog, Brittney, awakened him with her barking early Saturday in time for both of them to escape from his burning house in Grand Rapids.
The fire came two weeks after a veterinarian discovered the 9-year-old American bulldog had several cancerous tumors.
The vet said the dog might not survive surgery, and Seymour ruled out chemotherapy, believing it would be too hard on Brittney.
Seymour said he could have had Brittney put down, but instead decided to give her medication to blunt her pain until death comes naturally, probably within a few weeks.
Firefighters told The Grand Rapids Press the house may be a total loss.