Toxic plants & Trees and your horse
Thankfully, horses usually avoid toxic plants. After all, most poisonous plants are distasteful. Horses are also much larger than dogs, cats, and humans. So where a nibble of some plants may instantly poison you or your other pets, horses have a little leeway. In other words, your horse would have to consume a significant amount of certain less toxic plants to feel any effects. Although it may not consume large quantities at any given time, the build-up from months of consumption can make the animal sick or may even be fatal.