Oleander (Nerium oleander) in Pets

Every part of an oleander contains heart glycosides. Learn why no safe amount is published, which signs show heart involvement and why burning oleander clippings is also dangerous.

What It Is

Oleander is a hardy flowering shrub whose leaves, flowers, stems, sap and seeds all contain cardiac glycosides, mainly oleandrin. These compounds act like an overdose of the heart drug digoxin: they disturb the sodium-potassium pump in heart muscle and cause dangerous rhythms. Dried leaves and clippings stay toxic.

Where Pets Come Across It

Hedges and ornamental shrubs in warm regions such as the Mediterranean, California, the US South and Australia, plus potted oleanders on patios elsewhere. Dogs chew fallen leaves or sticks; horses and livestock are poisoned by hedge trimmings thrown into fields.

Which Animals Are Affected

Dogs, cats, horses, cattle, goats and birds are all susceptible. Grazing animals are poisoned most often and most severely.

Published Toxic Dose

No reliable owner-usable mg/kg threshold is published for dogs or cats, because glycoside content varies between plants and plant parts. The ASPCA and Pet Poison Helpline classify oleander as highly toxic to pets, and small amounts of leaf have caused serious heart problems. The calculator does not attach a risk level to a milligram figure for oleander.

Signs and How Soon They Appear

Drooling, vomiting (sometimes bloody), diarrhoea and abdominal pain usually start within a few hours. Heart effects follow: a slow, fast or irregular pulse, weakness, cold limbs, collapse and, in severe cases, death.

What to Do Right Now

Call your vet or a poison line now and say the word 'oleander'; the heart needs monitoring even if your pet only vomits. Take a leaf or photo with you. Do not induce vomiting at home. Never burn oleander clippings near animals; the smoke is also harmful.

Oleander in gardens, hedges and holiday rentals

Oleander is planted for its drought tolerance, so it lines motorways, school grounds and holiday villas across the Mediterranean, the US Sun Belt and Australia. Dogs travelling with their owners meet it in unfamiliar gardens, often as sticks to chew or leaves blown onto a patio. Leaves are long, narrow and leathery, about 10–20 cm, arranged in whorls of three, and the flowers are pink, red, white or yellow clusters at the branch tips. If you rent a holiday home, check the garden before letting a dog roam, pick up fallen leaves, and never use oleander wood for barbecue skewers or campfires. Composted oleander is also unsafe for gardens used by animals. Owners of horses or goats should make sure neighbours do not dump hedge cuttings over the fence.

Yellow oleander and other relatives

Yellow oleander (Cascabela thevetia, formerly Thevetia peruviana) is a different plant with similar heart glycosides and is common in tropical gardens, including South Asia, the Caribbean and northern Australia. Its seeds are especially dangerous. Desert rose (Adenium obesum), a popular bonsai-style succulent, belongs to the same plant family and also contains cardiac glycosides. When you call a poison line, describe the plant or send a photo rather than relying on the name 'oleander', because local common names vary widely between countries.

Frequently Asked Questions

Sources and References

• ASPCA: Oleander
• Pet Poison Helpline: Oleander
• Merck Veterinary Manual: Houseplants and Ornamentals Toxic to Animals

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