Which tree is poisonous to horses?

• A. Pine
• B. Birch
• C. Sycamore
• D. Maple

Answer: (C)

Horses can be harmed by certain trees if they chew or ingest their leaves. In particular, members of the maple family can cause oxidative damage to red blood cells when eaten, especially wilted leaves that have fallen to the ground. This can lead to Heinz body anemia and serious illness. Because sycamore is a maple-like tree that is commonly flagged as poisonous to horses, it’s the best answer here. The other trees listed aren’t typically cited as major poisonous hazards for horses in standard guides, so they’re less likely to cause the problem described.