He's Just Sleeping

People know horses sleep standing up but not as many know they wil sleep lying down too so everyone freaks out and think the horse died when he's just trying to nap

yeah, but that's not what Lucifer was saying. It was more why say "WARNING"? What's going to happen that needs warning against?

It's a real problem for farmers, people calling in because of supposed animal cruelty. There's a sickness in cows called '3-day sickness' cause they literally just lie down for 3 days and there's nothing you can do for them, just put them in shade and some water nearby. A dairy I worked at had a cow get 3-day next to a roadside, and the RSPCA got called so many times, people came up to the gate and just yelled profanities at us without listening, so we had to put up a similar sign too.

They do. They just lay down sleeping if they feel very safe.