Welsummerchicks, are you talking about the deadly impacted colic? If so, laxatives are BAD if they are impacted or the intestines are twisted up badly that the tissues are dying. It would be deadly, that is for sure. If one is not quick enough, or face the uncertainty of what kind of colic we are dealing with, surgery either would help or make haste with the horse's maker to its death.
Any horses that colicked, I'd rather have the vet come out and go broke than losing a horse even I have some experience in vet medicine. I don't want to play Russian Roulette with colic, no matter how minor or major the horse has.
I had a Paso gelding which he did show signs of colic but the vet said he has gut sounds but with the weather, which it rained alot with grass, it made his stomach upset possibly from the field run offs. Vet went ahead and tubed him and told me to keep an eye out, making sure he is pooping. Yep a messy job but gelding was fine. Even he may not need to lube up the gelding but to be on the safe side for the err of margin, it could not hurt at all trying. That was the only time I've had horses that colicked or possibly colicked on me for years but the vet is a good friend to have when you have horses. It gives me a peace of mind as well.
Self treatments, they do have their place and you know the risks so OP is very lucky there and hopefully the feed bin will be locked up or put a spring on the door to keep the horses from getting into it. We all take chances when we self medicate livestock and if the animal dies in our care, then we have to own up to it and learn from it what if it would have been done differently. I won't beat on OP for her decision but just say that she is very lucky there. VERY lucky.
IMO, I would not self medicate a horse with colic. I'd rather call up the vet on a false alarm than something that will go downhill fast or crippled forever.
In my vet schooling days, colic is not a quick death. Its very painful and horses DO need our help when crisis occurs. Amish vets are not the same as our equine vets even they may have gone to the same school but the Amish view horses as transportation, a beast of burden and they don't devote all of their resources and time on their horses as prima donnas like we do for our own horses. They make money off of their Standardbred broodmares, churning them out to be broke to buggies, rarely ridden. Same for draft horses. One horse dies, well, they just get a back up by borrowing a neighbor's horse until they can get the resources to buy their own horse. We dont live too far from many of the Amish communities and many of them of the drivers think of their horses as commodities, nothing else. Very few Amish folks would "treasure" their own horses, giving them the best feed, etc. and treated them kindly, making sure their legs are not puffy, or going lame. They don't judge colic on basis what is happening to the horse, "oh, a gallon of this oil will cure it all". Not all would do this method but most of them do. Most of them could not afford or have the luxury to have surgeries on their horses. Amish do NOT "humanize" their horses like we do or have the tendency to do with our horses and pets.