How do I get a pig past the world border in Minecraft?

Solution 1:

You aren't supposed to be able to get past the world border. That it works with an ender pearl is a bug. Entities freeze beyond the world border, because they shouldn't be there anyway, the world is meant to end there. By default the world border would even kill them.

So there is no way to get them to move, other than teleporting them around or similar.