Tamed Dogs and Cats standing up and teleporting on their own.

Sometimes I right click on a dog or cat to make them sit down, hence they arn't supposed to teleport. However sometimes when I leave them they still teleport to me. This claims that they somehow stand up on their own, or they still teleport if sitting down.

This is rather annoying seeing as I usually have a pen for them, and getting them in isn't as easy as it seems.