Red oak-Quercus rubra L.-Poisonous plant

Red oak

General poisoning notes:

Red oak (Quercus rubra) is a native tree found in eastern Canada. This plant contains toxic tannins that have caused poisoning and death in cattle and horses. Sheep may have also been poisoned by this oak. Poisoning can lead to depression, anorexia, loss of condition, and kidney damage. Kidney failure usually results in death (Duncan 1961, Cockerill and Beasley 1979).

Description

Trees , deciduous, to 30 m. Bark gray or dark gray, ridges wide, shiny, separated by shallow fissures, inner bark pinkish. Twigs reddish brown, 2-3.5(-4.5) mm diam., glabrous. Terminal buds dark reddish brown, ovoid to ellipsoid, 4-7 mm, glabrous or with tuft of reddish hairs at apex. Leaves: petiole 25-50 mm, glabrous, often red tinged. Leaf blade ovate to elliptic or obovate, 120-200 × 60-120 mm, base broadly cuneate to almost truncate, margins with 7-11 lobes and 12-50 awns, lobes oblong, occasionally distally expanded, separated by shallow sinuses, sinuses usually extending less than 1/2 distance to midrib, apex acute; surfaces abaxially pale green, often glaucous, glabrous except for minute axillary tufts of tomentum, adaxially dull green, glabrous, secondary veins raised on both surfaces. Acorns biennial; cup saucer- to cup-shaped, 5-12 mm high × 18-30 mm wide, covering 1/4-1/3 nut, outer surface puberulent, inner surface light brown to red-brown, glabrous or with ring of pubescence around scar, scales less than 4 mm, often with dark margins, tips tightly appressed, obtuse; nut ovoid to oblong, 15-30 × 10-21 mm, glabrous, scar diam. 6.5-12.5 mm. 2 n = 24.

Nomenclature:

Scientific Name: Quercus rubra L.

Vernacular name(s): red oak

Scientific family name: Fagaceae

Vernacular family name: beech

Geographic Information

New Brunswick,Nova Scotia, Ontario, Prince Edward Island, Quebec.

Notes on Poisonous plant parts:

The leaves and acorns are toxic. The immature acorns contain more toxin than the mature acorns (Cockrill and Beasley 1979).

Toxic parts:

Acorns, immature fruit, leaves

Notes on Toxic plant chemicals:

The toxic agents are polyhydroxyphenolic compounds (tannins) including gallic acid, pyrogallol, and tannic acid. The concentration of these compounds is higher in immature, green acorns than in mature ones. The following quantities of phenolics were found in acorns (Basden and Dalvi 1987):

Oak species	Total phenolics (% of total weight)
Quercus alba (white oak)	1.09 (0.41-2.54)
Quercus rubra (red oak)	3.72
Quercus velutina (black oak)	4.51 (3.29-6.13)

Black oak and red oak contain a greater total average of phenolics in the acorns does than white oak.

Toxic plant chemicals:

Gallic acid, pyrogallol, tannic acid.

Animals/Human Poisoning:

Note: When an animal is listed without additional information, the literature (as of 1993) contained no detailed explanation.

Cattle

General symptoms of poisoning:

Anorexia, constipation, depression, kidney failure, teeth grinding.

Notes on poisoning:

Cattle that ingest a small number of acorns may show some loss of condition. However, they often develop a preference for eating the acorns. Toxic amounts cause depression, anorexia, constipation, the passing of small fecal balls covered in mucous and blood, teeth grinding, and submandibular edema. Death is usually caused by kidney failure. Postmortem findings reveal a large number of acorns in the rumen, gastroenteritis in the caudal portion of the digestive tract, and small, shrunken kidneys with diminished reserve capacity. If renal stress occurs, the reserve function of the kidney may be exceeded. Perirenal edema and hemorrhagic enteritis were the prominent lesions. Multifocal necrosis of the proximal convoluted tubules of the kidney is characteristic (Sandusky et al. 1977, Cockrill and Beasley 1979).

Horses

General symptoms of poisoning:

Abdominal pains, anorexia, colic, constipation, depression, diarrhea, hematuria, icterus.

Notes on poisoning:

Horses that ingested leaves of red oak developed symptoms of depression, anorexia, abdominal pain, constipation, slight icterus, hematuria, edema, and weakness. The symptoms occurred 6-9 days after ingestion. Blood transfusions were thought to speed recovery (Duncan 1961).

Sheep