M.P.
I don't know of any books, but I thought I would share a funny story that may help you take a different perspective. We have two cats, one of whom ran away in the fall. We think that a fox or coyote got ahold of him (we live out in the country). One day my three year old (who had been fairly upset that the cat was gone) told my babysitter "Snickers ran away. He got eaten by a wolf...or maybe a dying moose." A DYING MOOSE!!! In upstate NY? And not just a moose, a DYING moose!! Kids come up with things all on their own that totally change their perspective on things. We just gave him time to think it through and rationalize it on his own. We let him allow himself to think of the possibility that maybe he got eaten by a bigger animal and that that is just the way the world works with animals. Then he came up with this hysterical story all on his own. Now he knows that we tell the story a lot and everyone laughs and he focuses on that rather than on the cat having gone missing (he loves to make people laugh!) I hope maybe that helps a little! Good luck!!