52. Oleander

Nerium oleander

Apocynaceae (Dogbane family)

TOXICITY RATING: High. Ingestion of even small amounts can kill.

ANIMALS AFFECTED: All animals can be affected.

DANGEROUS PARTS OF PLANT: The entire plant is toxic. Most animals are poisoned by consuming leaves, fresh or dried.

CLASS OF SIGNS: Gastrointestinal irritation, cardiac abnormalities, death (may be sudden).

PLANT DESCRIPTION: This plant grows outdoors in warmer regions, and in Indiana is grown as a houseplant. Oleander grows as a shrub or sometimes to the size of a small tree. The leaves are lance-shaped, thick and leathery, and grow opposite each other. Sometimes, leaves may grow in whorls. The leaves are 8 to 10 inches long, although smaller specimens will have shorter leaves. Flowers are showy, approximately 1 to 3 inches in diameter, and grow in large clusters at the ends of the branches, and can be white or any shade of pink or red.

SIGNS: Oleander contains the toxins oleandrin and nerioside, which very similar to the toxins in foxglove (Digitalis). This is a tropical plant, but is grown as an ornamental and as a houseplant in Indiana. Apparently the plant is not palatable, but will be eaten by hungry animals. It is reported that dried or wilted leaves may be slightly more palatable than fresh leaves, and the leaves are still toxic when wilted or dried. In one report with horses, it was indicated that approximately 1/4 pound of leaves (about 30 or 40 leaves) could deliver a lethal dose to an adult horse.

Clinical signs may develop rapidly, and the animal may be found dead with no prior warning. In other cases, depression coupled with gastrointestinal distress is evident: vomiting (in those species that can vomit), diarrhea (which may be bloody), and abdominal pain. Irregularities in the heart rate and rhythm will occur: the heart may speed up or slow down, and beat erratically. As the toxicosis progresses, the extremities may become cold and the mucous membranes pale. Trembling and collapse can occur, followed by coma and death within a few hours.

FIRST AID: If animals are observed eating oleander, contact a veterinarian immediately. The toxin acts quickly, and is lethal in small amounts. Emergency measures may be used to empty the gastrointestinal tract of remaining plant matter, and medications may be administered to control the effects that the toxin has on the heart. Despite emergency care, the animal may still die, but the sooner treatment is begun, the better the prognosis for survival.

SAFETY IN PREPARED FEEDS: Oleander is extremely toxic, even in small quantities, and the toxin is not eliminated by drying. Therefore, feeds containing oleander are never safe for consumption.

PREVENTION: Be able to identify oleander and exercise extreme caution when pets (and humans) are in the vicinity of these plants. The plants should never be placed where animals can have contact with them. Extra care needs to be taken in cases where leaves can fall into a pasture or in the vicinity of a confined, bored or hungry animal.