There are Giant Slogs in the cave part of the Meep Herder Village.
And also maybe the Vykkers pumped slogs with staroids like they did with sligs you ever think about that? Maybe the Giant slog is for the Big Bro slig.
You know how a slog is a sligs best friend well a giant slog is a Big bro sligs best friend. It makes perfect sense. The bigger the slig the bigger the slog.