There are many plants that can be poisonous when eaten by a horse. All can be fatal if enough is eaten. Here are a few of the main culprits:
Yew leaves and twigs are extremely dangerous if a horse eats even a small amount. Horses may be found dead with leaves still in their mouths. There is no treatment.
St. John’s Wort can cause liver damage and sun sensitivity.
Horsetail and Bracken
Acorns and Oak leaves due to their high tannin content, which can cause kidney damage.
Oleander: disrupts the heartbeat.
Yellow Star Thistle
To help a horse recover from poisoning, be sure to give Transfer Factor to promote healing, strengthen the immune system, and reduce inflammation.