I own horses and IMO the meat is dangerous. First of all, on the wormers there is a large warning saying not to use it on livestock destined for the food table. Second, horses are not tracked like cows are as they move through life toward the food chain. On top of the wormers, unethical racehorse owners use medicines such as dexomorphine, which is 100 times stronger than morphine in their horses. And that is just two chemicals we know about.
There is no way to tell what substances have been given to the horse. The meat is therefore unsafe.
Many European countries have banned horse meat from the Americas for this reason,