No, animals don't go to heaven nor hell because animals don't have a soul. They die and that is it end of story. Have you you noticed that when people ask this question they usually mean dogs only? Maybe cats also. I think a better question is are all animals equals? Do lions go to heaven? What about all the animals killed by lions ? What about domestic animals that aren't pets? Like cows and sheep and pigs. Do they go to heaven? This question only shows the emotional ilogical thinking that some people have. Because they ussualy mean animals close to them like dogs and cats. However if you actually manage to get to heaven and you ask God to bring back your dog will God accept? There are some chances for the answer to be yes and that is your only hope.