If it is just a matter of the dog coming to the hole in the fence and barking and whining, it may not be anything other than the fact that the dog has received something to eat there once before and is trying for a repeat. I have given my neighbors dog a treat maybe once every 4 months, yet whenever we are outside at the same time they are at the fence yelping and licking their lips like it is a daily occurance. I wouldn't jump to any conclusions based on just this and the fact that the yard is messy.