Most cases of maple intoxication occur during the late spring, summer, or early fall. Some animals have been poisoned after consuming bark poisoning usually follows windstorms after which downed trees and limbs become available to the horses.

Fresh green leaves are not toxic but can remain toxic for up to 30 days once dried.

Poisoning occurs when horses consume wilted or dry leaves equivalent to 1.5 to 3.0 grams of dry leaves per kilogram of body weight, or about 2 pounds of dry leaves for a 1,000-pound horse. Most of the intoxications reported have dealt with red maple, but field cases are also reported involving the consumption of Silver Maple with similar clinical signs. Feeding studies have confirmed the toxicity of Red Maple. Only the Red Maple and closely related hybrids are known to be toxic, but all species of maple should be considered potentially toxic to horses. The toxin in Red Maples oxidizes the hemoglobin with the formation of Heinz bodies, methemoglobinemia, and following hemolytic anemia. Toxic Agent The toxic agent of maple has not been identified. Red Maple can grow in most soils but grows better in slightly acidic and moist conditions. Red Maple trees may be found throughout the entire eastern half of the United States and Canada, including all regions of Texas. Native habitats include moist woods, stream banks, and floodplains. Box Elders are distributed across the United States, Canada, and Mexico. It displays tolerance to dry soil, but it needs moisture in brighter growing sites. The Chalk Maple can be found in rocky woods, river bluffs, or ravines. Native habitats include moist soils of canyons and woodlands. In Texas, they are found in the Trans-Pecos and Edwards Plateau regions. Bigtooth Maples are found in the western United States. Native habitats include streams and riverbanks. Habitat The Southern Sugar Maple can be found from Virginia to Florida, West to Kansas, and South to eastern Texas. Red Maples provide fall color as the leaves turn shades of yellow through orange or red. Leaves can be either smooth or hairy. The fruit is a samara that grows in pairs and is reddish to brown in color. Its three to five-lobed leaves are opposite each other on the stem, bright green above and whitish beneath. The Red Maple, often planted as an ornamental, has pink to red flowers borne in the spring, before the leaves. Red Maple trees typically grow 40 to 60 ft or 12 to 18 m however, they can reach heights over 100 feet or 30 meters. Its fruit is a one-seeded samara that droops in clusters. Blooming occurs from March to April with flowers being yellow, green, or brown in color, inconspicuous, in clusters, and appearing as leaves start to unfold. Its foliage color is insignificant in the fall. Young trees and new growth are bright olive-green. It differs from the other maple species since it has compound leaves with 3 to 9 leaflets. It commonly has a short trunk with wide-spreading branches. The Box Elder grows from 35 to 50 ft or 10.5 to 15 m tall. Bloom time occurs from April to May with yellow flowers. Its leaves may be smaller than other maple species, drooping, and gray-green underneath. Its mature bark is chalkily surfaced with a distinct white color. The Chalk Maple grows to 25 ft or 7.6 m tall and typically has two to three trunks. Flowers are inconspicuous, hang in clusters, appear with leaves, and are yellow to green in color.

It has a short trunk with a spreading, round, and dense crown. The lobed leaves are dark green on top and pale underneath which turn bright red or gold in the fall. Bigtooth Maple is a shrubby or tree-like maple that matures around 10 to 15 ft or 3 to 4.5 m tall. The samara fruit is ¾ inches long and matures in mid-summer. Small flowers hang from a stalk in clusters and are yellow to green in color. Its lobed leaves are green above and paler below. Its fall color is usually yellow and is not as vibrant. The Southern Sugar Maple is a small, spreading tree reaching 20 to 25 ft or 6 to 7.5 m tall. Description There are five species of the Maple family (Aceraceae) that are native to Texas which include the Southern Sugar Maple ( Acer floridanum ), Big-toothed Maple ( Acer grandidentatum ), Chalk Maple ( Acer leucoderme ), Boxelder or Ash-leaved Maple ( Acer negundo ), and Red Maple ( Acer rubrum ).

Different types of maple tree