What animals for through doorways?

Currently my tribe and I are boat people. We have a few boats that serve different rolls. we have one well built boat with everything one would need,the problem is we do not have a dino gate on the boat. The only way to get the animals out is to push them out with a rock or something. Are there any animals that can walk through doorways. I am trying to find a decent pacy to serve as a small mule, does anyone know how high a pacy's weight can get?