Unless it is a loose dog, in which case you need to report it, you could try putting a rude notice out so the owner sees it. Try to narrow down when it happens and see if you can catch it in the act.
Of course, it could be a cat although they usually cover it up.
You do what I did, wait until the offender arrives and leaves a present on your drive, you then hammer on the window, run out and chase the owner until he's out of breath and can't run anymore.
You then lead him/her back to your drive and give them a bag and politely ask them to pick it up, of course, the option of refusal is well, not an option.
I found it worked a treat I've never seen him or his dog again.