An all-seasons threat

Fallen, wilted or dried leaves from the red maple

(Acer rubrum) contain toxins that can cause fatal poisoning in horses and ponies as well as donkeys and mules.

Horses are most likely to encounter wilted leaves after summer storms bring down branches or blow leaves into pastures and paddocks. In the autumn, fallen maple leaves are generally less palatable to horses, but they also pose a serious threat if they are consumed. For an average horse, a leaf or two is not likely to cause harm but ingesting one to two pounds of wilted or dried leaves can result in severe illness or death.

Although the dangers of poisoning from the red maple, also called swamp maple or soft maple, are well known, research suggests that other trees of the species, including the sugar and silver maples and their hybrids, may also pose a threat.