Peer-reviewed veterinary case report
Horses getting weak and tired after eating red maple leaves?
By Divers, T J et al.·Published in Journal of the American Veterinary Medical Association·1982·View original on PubMed →
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Original publication title: Hemolytic anemia in horses after the ingestion of red maple leaves.
- Species:
- horse
Plain-English summary
Four adult horses from two farms in Georgia became very weak and showed signs of serious illness 3 to 4 days after eating wilted leaves from red maple trees. They experienced rapid breathing, a fast heartbeat, and a yellowing of their skin and eyes, along with brownish urine. Blood tests revealed that they had a dangerous condition where their red blood cells were breaking down, leading to low red blood cell counts and other serious changes. Sadly, three of the four horses died within 5 to 7 days after eating the leaves. The study confirmed that the toxic substance in red maple leaves can cause severe health issues in horses, and the treatment did not save the affected animals.
Abstract
Signs of acute hemolytic anemia developed in 4 adult horses from 2 Georgia farms 3 to 4 days after the ingestion of wilted leaves from cut red maple trees (Acer rubrum). Clinical findings included weakness, polypnea, tachycardia, depression, icterus, cyanosis, and brownish discoloration of the blood and urine. Blood changes included methemoglobinemia, free plasma hemoglobin, decreased pcv, and Heinz bodies in erythrocytes. These findings plus hemoglobinuria suggested intravascular hemolysis. Three of the 4 horses diet 5 to 7 days after ingestion of the leaves. Gross pathologic changes included generalized icterus, splenomegaly and swollen, black kidneys. Microscopic changes including tubular nephrosis with hemoglobin casts, vacuolization of centrilobular hepatocytes, and sequestration of erythrocytes in splenic sinusoids. A disease indistinguishable from the field cases was induced in a pony by the oral administration of dried, ground red maple leaves at a dosage of 1.5 g/kg. The findings of methemoglobinemia, hemolysis, and Heinz bodies suggested that the toxic principle of the red maple leaf was an oxidant.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/7056681/