Horses DO get killed by injection and only yesterday morning I heard of a bullock killed by anesthetic. So never take anything for granted.
If you're getting horse flesh ALWAYS find out how it died.
A horse put down by a vet using a general anesthetic has enough in it to kill dozens of dogs.
A horse killed by a humane bolt is 100%.
Horses get the bullet mate. Drugs work out expensive in horse doses and you cant use the meat, then have to dispose of it.
Bang bang Neddy.
When I mentioned that there's enough anesthetic in a horse to kill a lot of dogs that's because I've known where one dead horse fed caused over 20 hounds to die.
It's up to you if you want to take it for granted.
I can second Neil's warning.
I've known several horses killed by injection.