Looking for love in all the wrong places

Before we put up a fence, our crazy neighbor used to waltz into our yard and walk around like he owned the place. Once we fenced the yard, he started opening the gate and letting himself in. So we put a lock on the gate, whereupon he started looking over the fence by using a step ladder. Everyone up to speed? Good. Now, it seems, he thinks he has rights to our animals as well as our yard. Don't get me wrong-- I don't mind him trying to pet the cats, or chatting up Luke while John's walking him. But I take issue with our latest discovery: he brings Lydia inside his house. Let me repeat that, so it really sinks in: our ninety year-old neighbor has, heretofore unbeknownst to us and most certainly without our permission, been bringing one of our cats into his house. I'm so baffled by this latest revelation, so completely flabbergasted, that I don't even know what to say. And trust me, when you've done something to render ME speechless, you've pulled off quite a feat. How am I supposed to address this?