HORSE MULE DONKEY
The problem in fitting halters for long-eared equines is the general shape of their skulls. The horse has a long, relatively rectangular face.
The donkey is deeper through the jaw, but shorter in overall length. Its eye sockets are D-shaped, which accounts for the prominent brow ridges and the characteristic "sad" or "patient" expression.
The mule has a combination of the boxy shape of the horse's head, but with the deeper jaw. The mule's head, on average, may be slightly larger than that of a horse the same size.
Good Fit. Too Loose. Too Small/Tight.
While some tack and harness suppliers are starting to carry mule, donkey, and miniature halters to fit, you can alter a nylon halter. Punch a new hole in the crown with a hot nail or ice pick. To prevent fraying, singe the nylon at the hole.
Or you might buy a matching-colored lunge line, and ut of a portion to make a new nosepiece. Remove the old nosepiece first and use it as a pattern to cut a new one. Mark how much you have to add or take off, then cut the new section. Quickly singe the ends with a match or lighter to prevent fraying (caution, the edges will be melted and hot—don't touch! and don't breathe in the smoke). Attach the new nosepiece with heavy was thread. It can be done by hand, if you have a heavy needle, but many sewing machines can do heavy duty stitching.
A shoe repair or tack repair shop may be able to alter a leather halter. Take measurements of your animals' face to use as a guide for the alternations.