Materials that affect normal biochemical processes in the body are called either a toxin (plant or animal origin such as venom or a bacteria) or a poison (any substance that causes illness, teratogenic birth defects or death). Each topic addresses one of these. Thankfully there are few substances that overtly affect our domesticated horses but when they do, the results are usually fatal. These include animals (snake bites), bacteria (tetanus) and plants (yew, red maple, black wall nut shavings). Some can be transient such as the seasonal clover drools. Some can cause abortion of the fetus such as ergot mold. Some cause death.
More concerning are the toxins and poisons that are subtle in their effects. We don’t normally call them poisons but over time, they drain the horse of vitality or cause their premature death. These include heavy metals in the soil or the feeding of inflammatory food over years.
Avoidance is the key because with toxins and poisons, treatments often have poor results.
Acorns In Horses
In some parts of the United States and usually in August, horses can become sensitive to a fungus growing on clover that makes them excessively drool.
Creeping Indigo In Horses
The wilted red maple leaf (not the falling leaf in autumn) can destroy the kidneys of horses leading to renal failure and death.
Yew Shrubs In Horses