My DSIL has no kids but she does have a cat, who is her absolute world. Because the cat is a rescue he can't be locked in a room due to his previous trauma (I think?) so always needs to be roaming free in the house. The cat also, from the times I've visited, seems quite reluctant to be touched, can hiss if you come too near. Quite an unfriendly cat. Also a very fluffy cat.
For Xmas we are all going to my ILs house, me, my 2 DC, DH, DSIL and the cat. My kids are 11 months and 2.5. DC1 isn't always going to listen to instructions like "don't touch the cat" or "don't come near the cat" and DC2 is newly walking, leans on furniture when walking so there's a HIGH chance that one of the DCs will be hissed at or worse scratched by this cat. The only way to avoid it is to be 24/7 watching, not sit down for a minute for me and DH. DSIL says leaving him at home isnt an option because " the cat to her is what my DC are to me" (her words). locking him in a room, even for just xmas dinner so i can eat, is "cruel". The parents wont address it because DSIL is sad that shes single and this kitten is making her happy so they dont want to disturb that.
we are there for 2 full days, 3 nights. DH wont address it for similar reasons that PIL wont.