Three of my four are microchipped with AVID chips. I bought them thru Stolen Horse International because at that time, SSH got a small contribution back from AVID. That was 2004 so I don't know if they still do.
Ryle stated the pros and I do agree.
The cons are:
1. If your horse gets loose while you are away from home and goes missing, a micro-chip is not readily visible if some unsavory person manages to get their hands on it for the express purpose of running it thru an auction barn for a few dollars.
1.1 Those kinds of auction barns most likely do not have scanners to check every horse (and that is provided their scanner can read the brand name microchip in the horse's neck). Nor do they care
2. If the horse is found by an honest person, that person doesn't have a scanner (they were $200 when I checked prices in 2004), and many country vets don't have them either.
I would rather find someone that does the Cryogenic <--not sure that's the right word, freeze-brand, that is recognized nationwide. I THNK it is the same methods the Arabian Horse Association recognizes for freeze-branding Arabs.
I am only opposed to the lip tattos because the general population would not think to check the lip of a horse.
That all being said. I personally know of a bay Tennessee Walker that lived three miles from me and got stolen out of his pasture. He has his name "DOG" freeze-branded under his mane. That was over a year ago and the lady hasn't seen the horse since. She did find out who stole him but we live in a Good Ole Boy county where that kind of thing just gets shrugged off. Still-in-all, he has a freeze-brand and he's vanished into thin air.
Again, three of my four are micro-chipped but in reality, nothing is 100% when comes to getting a horse back that's gone missing
That was pretty much a "yes, I guess not" answer and probably only added further to the confusion. It's a crap shoot so a person has to do what they feel is best for the environment their horses will be in and pray they don't have to ever fall back on freeze brands, tattos, or micro-chips