[Porsche-O-Phile]

It was polite of them to ask.

It would be impolite of them to become indignant over your response.

I agree, you're the host, you have valid reasons - you set the rules. Just tell them you're sorry but the dog has been a problem in the past and although you enjoy them and their company, you're opening your home to enough chaos and disruption without adding to it unnecessarily.

I'm sure someone can take care of the dog or watch it for a few hours. What's the big deal?