The proper name for fire dogs is accelerant detection dogs and when I do school visits I find the one dog hero children know the least about is the fire dog. I'm not surprised as it was also the job I was least familiar with.
Fire dogs detect accelerants that help start or spread a fire and ultimately their work is used as evidence in court to help convict arsonists. I also learned that fire dogs perform field searches for evidence that the arsonist may have tried to hide. They can sniff clothes or other samples that may have been removed from the fire scene.