over the years when it rains or melting snow ect, my wife is always
cleaning the dog pen poop and it is a muddy mess at times, what are most
people putting in the pen to help this out, I was thinking of wood
chips, but before I do that, maybe someone has some better tips on what
to put down.

thanks
Chet

Wow, I can relate to this. I do not think that putting wood chips down would be a good idea. It would only add to the mess and clean up would be a lot harder.

My neighbor uses a shop vac to clean up after her pets. Does a good job although emptying the vacuum is gross.

What kind of surface is the pen? Dirt, grass or concrete?