You know, I was going to drop this. HOWEVER--
1-- No way you leave it in a guarded area? Fine. You\'re not working here.
2-- Make them return the empty vials.
3-- Nobody said you couldn\'t take the drugs out of your locker and carry them around from barn to barn. Assuming it really is necessary to work out of your truck, the way to do this would be instead of using a parking to toss a percentage of all trucks entering every day.
4-- The point was that in an emergency you would NOT have to go to your locker or the pharmacy, you could bring whatever you need. You would have to call security to observe either before or as soon as possible. They would NOT have to know anything about medicine, just to observe that you were there administering to a horse that was in distress. Nobody will be concerned about you giving illegal drugs to a horse that is not about to race.
5-- There is no reason to restrict it to one brand, but the answer is yes, they can do that, they can do anything they want. Ask the courts. You don\'t like it, work somewhere else.