You Find the Owner of the Footsteps.

Traveling a little bit further, upon a rocky sand embankment, you meet your "prey". Seems you were on the money about them being a canine, too.

A sleekly furred and muscled fox stands by the river, holding a rustic fishing rod. He's sweaty, wearing nothing more than one of those odd pieces of underwear you see from those artist's on twitter. Thin, wrapped white clothe covering just his front, leaving his entire ass out in plain view. Only slightly obscured by the fox's large tail swishing back and forth. If you were to guess, he's probably around the 5 foot mark, maybe a little bigger.

What was big, though, was the fox's bulge. It leaving the clothe holding whatever was in there straining, clearly. Even from this distance, even covered in all of that sweat.