As handoflixue said, potential for recreational use. (This even scares them about freaking bupropion, which doesn’t actually have any.) Long-term effects not well known, because horses rarely take the Beck depression inventory. Just plain bizarre effects given current model—depression does not normally goes away in an hour, and if it goes away in less than a week you panic, lock the patient up, and watch for signs of mania.
As handoflixue said, potential for recreational use. (This even scares them about freaking bupropion, which doesn’t actually have any.) Long-term effects not well known, because horses rarely take the Beck depression inventory. Just plain bizarre effects given current model—depression does not normally goes away in an hour, and if it goes away in less than a week you panic, lock the patient up, and watch for signs of mania.