Are there any trees that horses cannot be around?

Question

That are harmful if he would eat it?

Answer 1

I know the herb tansy, and Datura (jimson, or loco weed) are bad for animals

Answer 2

I knew of cherries and plums (wilting leaves contain cyanide) and locoweed, but when I did a websearch to find a link to support my answer, I found this site:  http://www.naturalhorsetraining.com/Pois...  - I'd never heard of red maple being harmful before!  These sites also mention it:  http://www.whmentors.org/saf/poison.html , http://www.aspca.org/site/PageServer?pag...