I would politely disagree with you
This can definitely be the case, but I wouldn't say drugging happens in the majority of these. We seem to get a lot of the same threads on HF and they nearly always have the same pattern - first-horse owner (generally young or an inexperienced adult), 3-4 weeks and a sudden personality change. As we ask more questions it becomes apparent that the issue is one of leadership.
The personality change may seem sudden but IME new owners fail to identify the escalating misbehaviour as that until it reaches a crisis point. The horse may have been doing little rude things like pinning ears, refusing to budge, nibbling, nudging, incessant rubbing etc before then - that doesn't seem like a big deal if you don't know what these actions mean, and some even seem cute and affectionate. Then, and it can seem like an overnight change, the horse decides "forget this, I'm the boss here and I don't want to go for a ride". hannahbanana
- was your horse stabled or paddocked before you got him? If he was paddocked, how many horses was he in with? Did he do anything that I mentioned in the previous paragraph before he decided to start biting and kicking?