In the episode of My Little Pony "Owl's Well That Ends Well", Pinkie Pie has a pear-like fruit in her bakery called a quince. However, I read somewhere that quinces are poisonous to equines (that includes horses and zebras alike).
This is a cartoon made for human beings, so naturally these equines are going to be given human-like qualities to make them easier to relate to. If it means disregarding not-so-obvious points about equine biology then so be it.
Can quinces really kill horses?