Something I have never been able to explain happened to one of my parents horses. The horse was very ill and my parents called various people to cure it but they could not do anything. Eventually in desperation my parents saw a friend who said he knew an Indian guru who healed horses. The guru came and stroked the horse with his hands for about ten minutes then said the horse is cured and asked my parents for money. My parents were not very pleased because the horse was still lying on the ground but they gave the guru the money. The next morning the horse was back on its feet and lived for years afterward. The reason the guru was recommended was because he allegedly had done the same for others.
When a human is sick with an unknown illness doctors do all sorts of exploratory surgery to find the cause.
I'll wager the horse was never taken to a vets and put under anesthetic and operated on. I'll wager also that the horse probably ate something that did not agree with it or even it had being bitten by a bat and was anaemic or had a reaction to poison from an insect.
There are a myriad of reasons the horse could have been sick. That a vet just looking could not tell which.
The so called healer could have seen the symptoms before or not and just said the horse would get well. nothing woo woo about it. Unless your gullible of course.