"This sort of deception sets up the kids for years of psychotherapy as adults," says LaFarge. "Tell the kids that Bella is sick or that she has a disease — and give it a name — if there is a name for what's wrong with her. Say, 'Soon, Bella will need our help to go to heaven. And we'll have to take her to the veterinary office so she will never hurt again.' Of course, these aren't going to be your exact words, but the idea is to be honest."
When it comes time to euthanize, LaFarge says, ideally take the children into the room so they can see how peaceful the process is.
"Some veterinarians are very good about this; others may not be," she says. "One reason you want to let the kids watch is that their imaginations may portray a picture far more terrifying than what really happens."
Of course, the 5-year-old may not grasp the notion of death and might ask for another dog an hour later. "That doesn't mean the 5-year-old didn't care about Bella. Other young children may be very distressed, and (you should) understand that is also normal," says LaFarge.
LaFarge adds that it helps to offer all an outlet for grief (for adults, as well as children) over the death of a beloved pet. The outlet for your kids might be coloring, burying some valued items belonging to Bella during a ceremony in which she is honored, reviewing a photo album, writing stories and/or speaking to friends/family members about feelings. There are many excellent books for kids about pet loss (available everywhere from Amazon.com to your local library).
Don't be afraid to let your kids see that Mom and Dad are sad, too. Indeed, Bella has been with you longer than your children — and of course, you will mourn her passing. I'm sorry for your impending loss.