I can imagine wild slogs also. Not only would there be a native wild breed, but there would also be Slogs that were once domesticated and have escaped or been "dumped" (like happens with the cats and dogs of our world
).
I don't think that Slogs are a creature that has been developed by the Vykkers. I think they are a native animal, however they have been trained by Sligs at an early age to act as guard dogs. Also, they have become victims of the Vykkers experiments, such as the large slogs and the water based slogs that we see in MO.
Abe Babe...