Did you know that a hinny is the offspring of a male horse and a female donkey, and a mule is the offspring of a female horse and male donkey. Also, mules used in the Grand Canyon are usually bred out of Quarter Horse mares to insure their compact size.
That bit of mule trivia is brought to you by my overriding (hah!) thoughts of Armand and Annie either being rear-ended by a mule train or having to follow a trail of mule poop in the desert heat!
I do hope they're safe in an air-conditioned, sweet smelling room somewhere.
Photo from The Grand Canyon Explorer