Honestly, I think kids are pretty capable of more than most folks think they are. I think kids of that age are honestly able to *see* that Poochie suffers. But then -- I even teach my DOGS to be "gentle" with an elderly one, or "leave him alone -- he's hurting".
I has to be within the family's belief structure -- Rainbow Bridge is a part of my own personal belief system. So for me it's a real place and real "relief". But I'd probably be discussing all along the way the whole idea of "quality of life". She still wants to be happy and wants to play with you. She enjoyed her supper tonight!
But I'd honestly make sure they see the pain. I'd probably also be preparing them with the reality that sometimes the vet can't make it better.
It's a process -- I always cringe when I see a family insulate children from things like pain and death. Sometimes we get better -- sometimes we don't.
I was reared in a home where I went to viewings at funeral homes from a pretty young age. Friends of the family who passed -- death wasn't something that was just 'sprung' on me when my parents couldn't hide it.
That's not a popular concept today -- I know people MY age who can't bring themselves to go to a funeral or go to a viewing because it "bothers" them -- and I think wow -- to me that's part of friendship. Of caring. Of helping a family deal. Of remembering and celebrating that life but acknowledging the pain of loss.
My point is -- if someone has to explain ALL of that to a child at once, that's incredibly hard. It's a wrench.
I used to go with my grandparents to visit friends of theirs at nursing homes and hospitals. So ... when someone passed I understood. Same thing with an animal.
But I guess my "short" answer (yeah, right -- this is ME???) is I think it has to be done as they go. An acknowledgement that the dog HAS cancer and life is precious. I'd be doing things NOW "You know what -- let's all go get ice cream and let's make sure Poochie goes with -- she can have a bit of strawberry!! She might not have many more times she CAN go."
That way every day is valued -- and as far as i'm concerned - it's the ONLY way to live life.