I heard microchip's were as stressful as hot branding, can't image how???? Dogs get microchips all the time, doesn't seem to bother them. If horse slaughter does start up again in the US, get your horse branded/chipped! Horse stealing will be on the rise again, unwanted/neglected horse numbers will stay the same.
I agree with Ellen, freeze branding is better. And I'm not sure why micro-chipping on horses isn't done.