Minecraft: How to stop mobs from despawning?

Like when I spawn a wolf, it will eventually despawn, and I was trying to build a petshop so I can't tame the dogs and cats, but I wanted to know what the gamerule was for mob despawning.

Not sure the gamerule for it but if you are in creative mode just name the animals. Also if you tame cats and dogs they don't despawn ever

From personal experience on both 360 and PC, put them in a small enclosed area with fences. If the are succeeds that of 20x20 they will despawn because their is to much room for the mobs to move. Hope it helps!

I'm pretty sure animals don't despawn. If they do, you can try editing the NBTedit tag "PersistenceRequired" to 1. This requires MCEdit and some knowledge in modding though. You should check out tutorials for this action before attempting to make any changes.

Animals don't despawn. They are probably escaping somehow.