The red maple tree is common throughout the eastern United States as a native tree. It grows naturally in many places, and is also planted purposefully for landscaping purposes throughout the United States.
The leaves of the this tree are the toxic culprit. They are toxic whether they are fresh, dried, or wilted, though the wilted ones are usually the problematic ones, as they blow into pastures during storms, or end up in lawn clippings given to horses.
If they are ingested at a rate of 0.3% of the horse's body weight (3 pounds for a 1000 pound horse) they can be deadly.
The exact toxic compound in this tree's leaves is not known, but whatever it is, it causes red blood cells to be destroyed.
Symptoms of poisoning are similar to those caused by other red blood cell diseases, and include:
There is no cure, or antidote for toxicity, therefore the best that the veterinarian can do is provide supportive therapy for the horse.
In extreme cases, a whole blood transfusion may be given to save the animal's life.
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