I think many use the canine fire type just because you are limited to using the Chinese Zodiac as fire animals. Charizard = Dragon; Typhlosion = Rodent; Blazekin = Roaster; Infernape = Monkey; Emboar = Pig; so people creating fakemon have a choice between the Rabbit, Snake, Goat, Horse, Tiger, Bull and of course the canine. So that is prob why there are many fire dog starters. Thank you for your nice words though.
At first when I started creating fakemon, I was unaware of this fact. Lucky for me, my first two sets of starter fakemon were a tiger and a dog. SO all I had yo do was change some of my future fire starter ideas.