I don't have a dog. I'd really like one but choose not to ATM because I have a cat and I don't have the time to do one justice.
MIL has a dog. Once it came to my house when it was in heat. She (inadvertently) scared my cats away for several days. And bled on my kitchen floor when DS1 was in his crawling stage, with all that involves. Since then I have said no dogs. And MIL respects that without question. She leaves the dog at home when she visits.
BIL now has a small bouncy poodle cross. It's very cute. But I don't want it in my house. Every time he visits he asks whether to bring it or leave it. We always say leave it. There is a back story, which would be better posted in Relationships, but suffice to say he's a selfish bully who hates my guts. We "play nice" but I feel the undertow.
I think it's his dog, his responsibility. It's not a child. If I was invited to something without my kids, I'd arrange a babysitter. The dog is really a puppy, about 18 months.