Houndoom- Spotted Hyena Inspired

The Houndoom I based on my dog was nice, but it didn't quite look savage enough, so I did a new one and based it's body structure more on a spotted hyena, and added some... artistic license... with its melty face and whatnot.
From a realistic perspective on its fiery abilities, I think something along the lines of a modified lung that stores flammable gas that, when exposed to air, combusts. This Houndoom might have used the fiery breath improperly a time or two, thus the melty face.