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 Brassica anemia 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.

References:

Cheeke, P. R., Shull, L. R. 1985. Natural toxicants in feeds and poisonous plants. AVI Publishing Company, Inc., Westport, Conn., USA. 492 pp.

Divers, T. J., George, L. W., George, J. W. 1982. Hemolytic anemia in horses after the ingestion of red maple leaves. Toxicology, 180: 300-302.

George, L. W., Divers, T. J., Mahaffey, E. A., Suarez, M. J. 1982. Heinz body anemia and methemoglobinemia in ponies given red maple (Acer rubrum L.) leaves. Vet. Pathol., 19: 521-533.

Long, P. H., Payne, J. W. 1984. Red maple-associated pulmonary thrombosis in a horse. J. Am. Vet. Med. Assoc., 184: 977-978.

Plumlee, K. H. 1991. Red maple toxicity in a horse. Vet. Hum. Toxicol., 33: 66-67.

Tennant, B., Dill, S. G., Glickman, L. T., Mirro, E. J., King, J. M., Polak, D. M., Smith, M. C., Kradel, D. C. 1981. Acute hemolytic anemia, methemoglobinemia, and Heinz body formation associated with ingestion of red maple leaves by horses. J. Am. Vet. Med. Assoc., 179: 143-150.

Nomenclature:

Scientific Name: Acer rubrum L.

Vernacular name(s): red maple

Scientific family name: Aceraceae

Vernacular family name: maple

Go to ITIS*^ca for more taxonomic information on: Acer rubrum

References:

Agriculture Quebec. 1975. Noms des maladies des plantes du Canada/ Names of plant diseases in Canada. , Quebec City, Que., Canada. 288 pp.

Alex, J. F., Cayouette, R., Mulligan, G. A. 1980. Common and botanical names of weeds in Canada/Noms populaire et scientifiques des plantes nuisibles du Canada. Revised. Agric. Can. Publ., Ottawa, Ont., Canada. 132 pp.

Bailey, L. H., Bailey, E. Z. 1976. Hortus third. Revised. MacMillan, New York, N.Y., USA. 1290 pp.

Scoggan, H. J. 1978, 1979. The flora of Canada. Nat. Mus. Nat. Sci. (Ottawa) Publ. Bot. 7(1)-7(4). 1711 pp.

Van Wijk, H. L. 1911. A dictionary of plant names. Martinus Nijhoff, The Hague, The Netherlands. 1444 pp.

Victorin, M. 1964. Flore Laurentienne. 2nd ed. Univ. Montreal, Montreal, Que., Canada. 952 pp.

Geographic Information

New Brunswick
Newfoundland
Nova Scotia
Ontario
Prince Edward Island
Quebec

References:

Bailey, L. H., Bailey, E. Z. 1976. Hortus third. Revised. MacMillan, New York, N.Y., USA. 1290 pp.

Boivin, B. 1966, 1967. Énumération des plantes du Canada. Provencheria 6. Nat. Can. (Que.) 93: 253-274; 371-437; 583-646; 989-1063. 94: 131-157; 471-528; 625-655.

Image or illustration

red maple:

Images: images.google.com

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

References:

Cheeke, P. R., Shull, L. R. 1985. Natural toxicants in feeds and poisonous plants. AVI Publishing Company, Inc., Westport, Conn., USA. 492 pp.

Divers, T. J., George, L. W., George, J. W. 1982. Hemolytic anemia in horses after the ingestion of red maple leaves. Toxicology, 180: 300-302.

George, L. W., Divers, T. J., Mahaffey, E. A., Suarez, M. J. 1982. Heinz body anemia and methemoglobinemia in ponies given red maple (Acer rubrum L.) leaves. Vet. Pathol., 19: 521-533.

Long, P. H., Payne, J. W. 1984. Red maple-associated pulmonary thrombosis in a horse. J. Am. Vet. Med. Assoc., 184: 977-978.

Plumlee, K. H. 1991. Red maple toxicity in a horse. Vet. Hum. Toxicol., 33: 66-67.

Tennant, B., Dill, S. G., Glickman, L. T., Mirro, E. J., King, J. M., Polak, D. M., Smith, M. C., Kradel, D. C. 1981. Acute hemolytic anemia, methemoglobinemia, and Heinz body formation associated with ingestion of red maple leaves by horses. J. Am. Vet. Med. Assoc., 179: 143-150.

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

References:

George, L. W., Divers, T. J., Mahaffey, E. A., Suarez, M. J. 1982. Heinz body anemia and methemoglobinemia in ponies given red maple (Acer rubrum L.) leaves. Vet. Pathol., 19: 521-533.

Tennant, B., Dill, S. G., Glickman, L. T., Mirro, E. J., King, J. M., Polak, D. M., Smith, M. C., Kradel, D. C. 1981. Acute hemolytic anemia, methemoglobinemia, and Heinz body formation associated with ingestion of red maple leaves by horses. J. Am. Vet. Med. Assoc., 179: 143-150.

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

References:

Divers, T. J., George, L. W., George, J. W. 1982. Hemolytic anemia in horses after the ingestion of red maple leaves. Toxicology, 180: 300-302.

George, L. W., Divers, T. J., Mahaffey, E. A., Suarez, M. J. 1982. Heinz body anemia and methemoglobinemia in ponies given red maple (Acer rubrum L.) leaves. Vet. Pathol., 19: 521-533.

Long, P. H., Payne, J. W. 1984. Red maple-associated pulmonary thrombosis in a horse. J. Am. Vet. Med. Assoc., 184: 977-978.

Plumlee, K. H. 1991. Red maple toxicity in a horse. Vet. Hum. Toxicol., 33: 66-67.