Well that one corner does look a little like a puppy chewed on it.
Looks to me like it's made with what they call wormy chestnut...
How long have you had it? Keep your eye on it and if there appears any little bits of saw dust or powdery stuff....then you need to get in inside a plastic tent and fumigate it. But the damage from powder post beetles doesn't look quite like that.
Linda C

The marks in the third pic down look like woodworm, but of the kind that is revealed after the wood is cut or sanded; woodworm prefer to work below the surface, and their entry point is small. When the wood is worked on, the burrows are brought to view.
The gnawed corner is another story, looks like a 4-legged critter.
Casey

Thanks so much! I was definitely thinking puppy when I saw the corner. How should I fix that? Should I sand it, and restain it?