What to look for in a guard donkey?

Think about one for my sheep.

Seems most folks who get a donkey or mule get protection for the animals the donkey/mule recognizes as its pack

...guess you could go on how you know a cat is a good mouser or not.  if the momma was a good mouser, the offspring are too (mule being sterile is an issue tho)

...I've known one person who purchased a mule and  another purchased a donkey for general protection, neither of the humans knew much about donkeys or mules but both did their protection thing at night

I've never seen a great pyrenees dog which failed to protect even the chickens, I get the feeling mules and donkeys are the same way..

....anybody ever see a donkey run and hide from a coyote or loose dogs?

-guess you could bring your dog to visit prospective the donkey; just don't let the donkey get close enough to bite the dog's neck!