Suspected red maple (Acer rubrum) toxicosis with abortion in two Percheron mares.

The research study discusses two cases of Percheron mares, who after consuming wilted leaves from red maple trees, aborted and developed a fatal blood disorder known as hemolytic anemia. The cause was suspected to be related to an unknown substance in the leaves of the red maple tree.

Context and Case Description

• The research involves two horses of the Percheron breed that developed severe hemolytic anemia—a condition wherein the red blood cells are destroyed faster than they can be made—and underwent abortion after consuming wilted leaves of the red maple tree.
• Though there isn’t a definitive diagnosis, the symptoms and laboratory results strongly suggested ‘red maple toxicosis’, a condition observed in horses that ingest parts of the red maple tree.

Red Maple Toxicosis and its Effects

• Red Maple toxicosis is suspected to be due to an unidentified oxidant present in the dried or wilted leaves of the tree.
• The ingestion of these leaves results in hemolytic anemia, which can often be severe and fatal.
• This study describes the severe health deficits, including fatal anemia and miscarriage, faced by the horses after they consumed the leaves.

Considerations and Differentials

• The authors emphasize that this diagnosis was considered reasonable based on visible symptoms and laboratory tests, despite the absence of complete antemortem and postmortem examinations.
• They also acknowledge different potential causes for the symptoms observed, such as equine infectious anemia, autoimmune hemolytic anemia, piroplasmosis, leptospirosis, ehrlichiosis, and exposure to other plant or chemical sources of oxidants (like onion, garlic, kale, and phenothiazines). However, these were ruled out based on the evident clinical signs and lab findings.