This is my thoughts on what happens when an animal dies. When I used to be a Christian they always talked about the afterlife and I always wondered what happened when an animal dies. Now I think I have I came up with an answer after reading "Animal Spirit Guides" by Steven D. Farmer.
I believe that when an animal dies it goes to the afterlife and is given the task of guiding and sending messages to us humans animal spirit guide. As for pets, I think that they are given a choice whether to become a spirit guide or spend the afterlife with their human family.
This is just my belief, what are your thoughts?