Horses and toxicity from fall leaves
Question: Between trail rides through the woods and wooded pastures, my horses are around a lot of fallen leaves in the fall. What leaves should I look out for?
Answer: As fall progresses and pastures begin to go dormant, fallen leaves could seem appetizing to some horses. Unfortunately, some leaves are toxic, including wilted maple leaves and fresh and wilted cherry leaves. Symptoms from consuming these leaves include red or brown urine and death, respectively. Although more of a summer issue, consumption of female boxelder seeds (e.g. samaras or “whirlybirds”) can cause seasonal pasture myopathy which can lead to death.
Fortunately, horses rarely consume wilted leaves. Most toxicity is seen when horses are left on over-grazed pasture without supplementing hay as hungry horses start consuming things they normally wouldn’t. Watching horses closely in the fall, supplementing hay when pastures begin to go dormant, and pulling horses off pastures during fall leaf shed are common strategies to reduce the risk of fall leaf toxicity. Most agree that wilted or fallen leaves are not toxic after going through a winter (e.g. the following spring).
Other tree-related toxicity issues include housing horses on shavings from black walnut and when horses consume green acorns from oaks. Fallen leaves from these tress are not normally associated with toxicity.