Red maple
General poisoning notes:
Red maple (Acer rubrum) is a native tree found in eastern Canada. Leaves of this plant have poisoned horses in the New England States and Georgia. Divers et al. (1982) noted that three of four horses died in one case. Experimental symptoms of hemolytic anemia indistinguishable from the field case were induced in a pony. This problem should be suspected in horses in which acute hemolytic anemia occurs after they ingest red maple leaves.
Horses are poisoned sporadically in the northeastern United States after they ingest red maple leaves. Signs of toxicity are similar to those seen with the Brassicaanemia factor after animals ingest plants of the genus Brassica (such as canola, kale, cabbage). Tennant et al. (1981) noted 33 cases of hemolytic anemia in horses in the New England States in the late 1970s. These cases were attributed to red maple leaves.
Nomenclature:
Scientific Name: Acer rubrum L.
Vernacular name(s): red maple
Scientific family name: Aceraceae
Vernacular family name: maple
Acer rubrum L.
Geographic Information
New Brunswick, Newfoundland, Nova Scotia, Ontario, Prince Edward Island, Quebec.
Notes on Poisonous plant parts:
The wilted leaves of red maple (Acer rubrum) have caused poisoning and death in horses. This toxicity is most prevalent from June through October. Cases become symptomatic 3-4 days after ingesting the leaves (Divers et al. 1982).
Wilted leaves administered to a pony at the rate of 3.0 g/kg of body weight caused illness and death within 1-5 days. Freshly harvested leaves did not cause any symptoms. Dried leaves remained toxic for 30 days (George et al. 1982).
Toxic parts:
Leaves.
Notes on Toxic plant chemicals:
The chemical that causes hemolytic anemia poisoning in horses is not yet known for red maple (Acer rubrum). The chemical probably works as an oxidant. In Georgia, ponies poisoned by red maple leaves died rapidly when fed dried leaves after mid September, whereas ponies fed leaves collected earlier in the summer had a more prolonged illness. This finding suggests that the toxin increases in quantity during autumn (George et al. 1982).
Toxic plant chemicals:
Unknown chemical.
Animals/Human Poisoning:
Note: When an animal is listed without additional information, the literature (as of 1993) contained no detailed explanation.
Horses
General symptoms of poisoning:
anorexia
blood brownish
brain, vacuolation of
breathing, rapid
coma
cyanosis
death
dehydration
depression
heart rate, elevated
Heinz bodies
hemoglobinuria
icterus
kidney, edema of
lungs, congestion of
lungs, thrombosis of
mucous membrane, brown
nephrosis, severe
urine, brownish
weakness.
