Grannygranby, if you are still reading here, it seems to me there are a lot of issues going on here all at once. The fact that DS (dear son) and family weren't there when you went to visit says to me that there is a conflict between DS and DIL or perhaps between you and DS (after all, why would he "forget to tell her?"). Or, as some have suggested, maybe you insisted on bringing your dogs and that created a problem?
It also sounds as if DS/DIL has an issue with your home, whether it's cuz of "doggieness" or whatever. And there's now a conflict between them and DD over the fact that DIL "won't tolerate (your) dogs in" DD's house during visits. Of course, DIL can't dictate where the dogs will be, so I take it you mean that DS,DIL and family refuse to come for Xmas, etc. if the dogs are in the house.
I also take it that you tried to strike a compromise between DS/DIL and DD/(yourself?) by suggesting the walk in the park. I know you meant well, but I don't think it was your place to do it. If DD has decided not to keep the dogs in the garden, this time around, then that's her right. And if DS and DIL choose not to come for that reason, that's their right. Sure, you'd like to have them all together on Xmas, but these things don't always work out. I don't know what ended up happening this Xmas, but from now on, you might have to arrange to see DS and family separately from DD on an alternate date, even if it just means going to a restaurant together and exchanging your Xmas gifts there.
I totally understand that your dogs are important to you. But I agree with those who say spending time with your DGC should mean more. If it doesn't, then, sad to say, IMO, you'll have to accept lowered contact with your DGC.
But you tell us your DIL has been hostile and outright "rude" to you from the beginning. I'm so sorry to hear that. Chances are, the "dog issue" is just a ruse to push you away then. Or, as some have said, it might be making a bad situation worse. Also, is it possible you were unintentionally insensitive to some issue of DIL's at the start, the way you seem to be regarding her concerns about dogs? I'm NOT saying you were, but if you can think of something, that may be your key to ending the animosity. Maybe not - just throwing out ideas, hoping something will be helpful.