A few months ago I wrote about practicing what you preach, and being sure that any animal you have in your care has the equipment and basic life skills to safely evacuate in event of a emergency.
And before the end of the year I completed my personal list by branding Brillo (companion mule) and pulling his coggins (on the rest of the herd's schedule, ensuring he'd be done each year in the future).
For 30 bucks and using one of the clinic's brands I provided sweet little B a unique, life long, forever visible mark (freeze brand- an 8 sideways/infinity sign).
Branding greatly reduces his chance of theft, while greatly increasing his chances at recovery.
Brillo is no longer just a little donkey looking mule, he is a little donkey looking mule with a brand (something anyone can look for). And his brand also helps to prove my ownership (in addition to his veterinary paper work since he doesn't have registration papers).
Even if you don't want to shell out $100-$200 on a custom brand (like the one on my mare above) you can still provide your beloved horses a permanent mark of "peace of mind".