If the ears are slightly backward then the horse is listening to what is behind them, they put their ears like this when they are sleeping as well. However, if they are flat back against the horses poll the they are showing that they are angry or distressed.
the horse is angry or generely not very happy
if the horses ears are slanted backwards it mean they might be unsure of angry
Howrse answer: angery
depends... it could mean it's angry and going to bite. Some horses ears are naturally back. sometimes they're smelling... Theres a few possible answers.
There are different degrees of 'backwards'. If his ears just flick back in a relaxed manner he is listening to something behind him. If his ears are pinned back flatter on his head he is sending a warning that he is not happy. It could result in a bite or a kick so when you see his ears like this be on your toes.
This means the horse is scared and afraid, and in some cases angry. You should calm him down by feeding it a treat or stroking him.
he's mad
The horse is angry.
Well if the horses ears are just slanted backwards a little it means the horse is listening to you. but if the horses ears are all the back where they are touching the back of there neck then they are very mad.
If your horse has it's ears slightly back then that means It's listening to something behind them. However, if your horse has it's ears pinned back all the way, then that means it's angry at or scared by something.
He/She is relaxed.
If the horses ears are pinned extremely far back, their head is raised, their eyes wild, the horse is frightened and angry, trying to tell you to back off. This is dangerous for you and the horse. If it's gentle, relaxed, it's probably listening to the ride or whats behind it. Or half asleep. =)