This was mishandled in several ways. First you as the owner have to be more proactive. If he’s down, you call the vet and insist they come immediately or at least that day.
All banamine does is eliminate pain. That is all it does. It is similar to you taking a bad fall off your horse and having some unknown internal injuries/broken ribs and just taking some opioids. You eliminated the pain but you don’t know how badly injured you are.
This is how banamine is abused. If my horse colics i am not going to give banamine. First I’m going to get a heart rate- a painful horse has an elevated heart rate and respiration. I’m also going to check temperature and capillary refill. Then i decide what to do. I give about 15-30 minutes of watch and wait, especially if symptoms are mild. The two times i had a horse gas colic, both passed with 15 minutes or so and the horse was back to normal. Colics due to gastric ulcers also pass rather quickly if you administer crushed tums as a paste and ranitidine. I look for risk factors for ulcers- high grain diet, in training, or in a new environment, ribby, etc.
The reason I do not administer anything is because if my horse gets more painful, i want to know about it. If my horse is laying quietly with colic, that is okay as well. The only time i would give banamine is if the horse is extremely distressed, rolling, high heart rate and respiration. Then give banamine and get the vet out asap.
My neighbor lost a horse the same way you did. They repeatedly gave banamine and missed the signs that things were serious. These things do happen unfortunately.
Someone i worked for lost a horse to colic. The horse was fine at breakfast, fine during stall cleaning at 10am. By 4 pm, he was in shock. His eyes turned red, he was ataxic. He had either twisted or had a severe impaction - this caused reflux to move up the throat and out the nostrils. It looked very similar to choke (swollen neck, nasal discharge) and the vet first thought choke, but quickly determined it was a severe colic. There was nothing the vet could do. The vet said it was the worst colic he had seen, only one time prior in his career did he see a horse present like that. It took 1 hour to walk the horse 40 ft to the roundpen for euthanasia because the horse was so ataxic he could barely walk with falling into things or circling. RIP poor boy.
Banamine blocks pain for 6-12 hours. If you use banamine, and don’t treat the cause, the horse will be painful again when the drug wears off. If it’s 2 pm and the horse is colicy i won’t administer banamine, because i don’t want to still have a sick horse at 1 am at night.
Sorry for your loss. Please tell all your friends about the dangers of banamine for colic. You can save other horses from a similar fate.