I wouldn't tell either, but as I've mentioned here I have been thinking about getting a small, quiet dog, but even the thought of someone telling on me kind of makes me feel like I should just stick to having goldfish and call it a day.
The landlord might change his mind about pets. What I find "funny" is that he has all sorts of rules that people don't follow, but he's kind of the "as long as I don't know about it" type. He's a good landlord, so I obey the rules so that I don't have to feel guilty or fake whenever he's talking to me. Other people break the rules but smile in his face. I just don't have that kind of energy... it seems too draining to put on a constant show like that for somebody.