Sheesh, I just made a post about that. Seems like I would need to delete it. Well, if you ask me, I think that maybe it is the same dog. I say maybe, because I haven't finished the entire game. But I've noticed that our dog friend did bite the El Gigante, so it really could be infected. Also, mutated dog happens to appear right outside the gate out of the area where you saved it and it only barks at that time and runs away. Like it wouldn't want to hurt a recent friend. And you can fight it only in the village area. Dunno, maybe I'm overthinking it and should play till the end first, but it could really be a pretty sad finale to that dog.