Wording could be taken either way, and I could be wrong, but it almost sounds like the dog was not on the property of its owner, and was over the fence in the neighbours property?
We have a huge problem with pet cats that stray from their properties and eat birds/fish/etc in neighbouring properties... if one turns up on my property, I trap it and send it to the shelter specifically so the owner gets fined, even though I know who owns it. It's what our local council/government recommend we do considering the owners already know it's illegal for pet cats to be off their property here (or even outside of their house after dark, which is almost always when we trap them in our yard).