A Janesville home on Henke Road caught on fire Thursday night around 8:58 p.m., a fire department release said.
When the Janesville Fire Department unit arrived at the scene, firefighters found heavy fire conditions on the first-floor interior and the north exterior wall extending to the second-floor exterior and attic.
The release said family members of the owner were present, but said there was no one home apart from a dog inside.
The fire was brought under control 30 minutes after arrival. Crews stayed at the scene for three hours to extinguish the fire.
A dog was found dead in the building, but no other injuries were reported. The cause of the fire is still under investigation.