Originally Posted by Vidaloco
It could be just a new environment rather than a drugged horse. Some horses are calm and friendly on the home turf. Then when you get them home they are like a different animal. Not saying yours wasn't drugged, but the odds are that its just scared. Horses act out when they are afraid and unsure.
I agree. If you just got it, like within days, it's too soon to say the horse was drugged. If it was alert, perky, bright eyed and looking around when you bought it, it may just be startled at the new surroundings. Wait a week after arrival and if things haven't changed then I would be suspicious. A horse's feet are a sink for foreign substances that the liver either can't filter out or that reaches the feet before the liver, and if it was a high dosage your farrier might be able to see lines below the coronet band which would suggest drugging.