Colic has also been reported in poisoned horses. Treated animals usually survive. In the spring, while waiting for other forage to become available, animals should not be allowed to graze in woodland pastures where there are buckeye sprouts. Red maple is a large native tree found in moist woodlands and swamps throughout Ohio. Leaves are opposite, generally triangular with three or five lobes, coarsely toothed, and silvery white beneath.
Poisonings result from consumption of wilted leaves and have only been reported for horses.
Toxicity is most prevalent from June through October, but may be greatest in autumn foliage. Dried leaves are reported to remain toxic for 30 days. The cause of toxicity is not known. Primary effects are acute hemolytic anemia, methemoglobinemia, and Heinz body formation in the red blood cells. Symptoms develop three to four days after ingestion of leaves and include rapid breathing and heart rate, weakness, depression, jaundice, cyanosis, brownish discoloration of blood and urine, coma, and death.