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Although we did not have a red maple tree in our pasture, some leaves and limbs blew into our pasture during a storm.  Unfortunately, our horse ingested some of the leaves and she became acutely ill, requiring us to put her down.  Please let horse owners know of this danger and how they can prevent a needless death to a horse.

Red maple trees are common throughout most of eastern North America and south to Florida and Texas.  They adapt to moist or dry areas and often are planted as ornamentals because of their striking fall colors.

An unidentified toxin is present in the wilted or dried leaves of red maples; only the red maple and possibly closely related hybrids are known to be toxic.   Horses, ponies, and zebras appear to be the only animals affected by the toxin in red maples. The toxin causes damage to blood hemoglobin which results in hemolytic anemia.  Poisoning is more likely in the fall or after a storm when leaves of fallen branches become accessible to horses.  The fresh green leaves apparently are not toxic, but once dried they may remain toxic for up to 30 days.  The bark from red maple trees also is toxic. 

After they eat relatively small amounts of dried red maple leaves, horses exhibit clinical signs within 1 to 2 days.   Poisoning is characterized by an acute hemolytic anemia that causes weakness, increased respiratory and heart rates, bluish mucous membranes, jaundice, and a red-brown coloration of the urine. Pregnant mares may abort without showing other signs. 

Affected horses should be denied further access to red maple leaves and blood transfusions given as necessary. If clinical signs are observed, horse owners and/or handlers are advised to contact a veterinarian immediately.

Prevention of red maple poisoning is best accomplished by maintaining a good feeding program for horses and removing red maple leaves and fallen branches from access by horses.   It is not advisable to plant red maple trees in or closely surrounding horse enclosures.

If you have questions or problems with services or products regulated by the Georgia Department of Agricultur,e you may write Consumer Services, Georgia Department of Agriculture, 19 Martin Luther King Drive, Room 224, Atlanta, Georgia 30334 or call (404) 656-3645 (Atlanta metro area) or toll-free, 1-800-282-5852 (state wide).