How would you address this?

Very early one morning I observed a man walking his dog. As they approached our driveway - we have no gates - the dog (a bitch) came a few feet onto the drive and peed. He made no attempt to entice her off the driveway and back onto the path and we were left with a puddle of dog pee that would no doubt attract other dogs to do the same.
I wasn't dressed at the time so had no intention of confronting him there and then. But I am not sure how to address this; the dog didn't defacate, just peed, but it was the nonchalant attitude of the owner that irks me.