If you will go back and read the whole thread you will notice two things:
1. He has tripped over his own feet for the past 20 years. Vet has checked him out several times and ruled out everything except clumsiness.
2. We do not own him, he is owned by the BO and they will have him checked by a vet ASAP, even though I did not come right out and say that, I didn't think I needed to. I did say the BO was doing everything they needed to do to make sure he was ok. They will be calling the vet in the morning because he was walking, eating, grazing, urinating, and pooping normally within a few minutes and hours of the incident. But yes, he will get a complete work up from the vet this week.
Heart attack. Well most animals including the one writing this die of something. Natural causes is often quoted as the cause but what is natural causes. How about this for a starter the heart stops while one is asleep.
Horses as all animals do have heart attacks I disagree with the other poster when she said few horses have heart attacks. The heart is a muscle that is subject to strain just like any other with a difference. It does not get to rest when hurt. Horses because of the kind of work we, yes we, put them through do colapse and die from heart attacks and the older one is the closer they are getting to maybe a heart problem, just like us. But like us keeping them fit and in work can and does enhance the quality of life.
Getting up after a heart attack is normal and the pain caused by the attack will cause the animal to moan as will the attention it was recieving, is the horse a talker. My wifes horse Kate is always talking and is quite the entertainer when on treks.
Back to the heart. If it does not kill then returning to activity and eating the same day is normal, but dependant on the severity and damage done. The chance of it happening again in a short space of time, 6 weeks or so is the danger time for all animals. Remember, unlike other musels the heart can not be placed in a splint or immobilised so until it is certian caution is required for your husbands safety and I am sure he will take care of the horse even though it is not your own. Corgi for your husbands safety walk the horse for a few weeks to be on the safe side that is unless a vet has pronounced it fit.