I can see why you found that upsetting.
Still: our society (rationally) does not devote the same resources to drug development for animals as it does for humans. And even protocols, dosing regimens, etc, for humans are not perfect. And even when the ideal protocol is chosen, some people still have a bad outcome by being an outlier.
Medicine is very imperfect; veterinary medicine is worse.
I suppose this sentence is meant to be a little tongue in cheek, but a few of us at least do not find it funny.