Fall leaves, especially red maple, can be toxic to horses, livestock and small ungulates. While we enjoy the colors and fall activities, a wind-cast limb from a maple could provide toxic leaves in the pasture.
Toxins, especially those in red maple, damage the hemoglobin in horses’ red blood cells, so they can no longer carry oxygen. Affected cells may rupture, clogging the kidneys with waste products, and the liver and spleen will remove damaged cells from the bloodstream faster than they can be replaced by the bone marrow, which results in severe anemia.
The 2020 Fall Foliage Prediction Map is a good tool to use to remind horse and livestock owners of fall leaf risks. It is also good for planning your fall colors viewing trips. < link >
Source: EQUUS, July 2019. Link.
Also see: Search Results for: fall foliage, Animal Health Digest. Link.