Materials Needed:
10 Wood Planks
6 Wood Stairs
2 Colored Wool
2 Wooden Fences
1 Gate
1 Signpost
First place the wood planks in a rectange that is 3×3, leaving the middle space open and a space beside it (which will be the opening. In the two spots you left open, min down 1 square and fill these spaces with your wool choice.
Now, place the stairs on the sides, so they face out, and put the remaining planks in the middle 3 slots. From here, place a fence post on either side of the door, with a gate between them. And finally, you can put a signpost above the gate with your dogs name (if you desire).
You can get your dog in here using meat, or just pushing him, and close the gate so you know where he is.