- Highly toxic — affects the heart
- Within hours
- Affects: Heart rhythm
Why this verdict for dogs
Oleander is extremely toxic — every part contains cardiac glycosides that affect the heart, and even a small amount can be life-threatening.
Warning signs to watch for
- Vomiting & drooling
- Abnormal heart rate
- Weakness
- Collapse
⚠ If your dog ate oleander
Act immediately — don't wait for symptoms.
- Call your vet or a pet poison helpline right away.
- Note how much was eaten and when.
- Do not induce vomiting unless a professional tells you to.
Oleander is a beautiful, drought-tolerant shrub planted along roadsides and in gardens across warm regions — and it is one of the most reliably lethal plants a pet can chew. Its toxins act directly on the heart, in the same way as a heart medication given at a massive overdose.
How much is safe?
Every part is toxic, and the dose required is small — a few leaves can be enough to kill a dog. The toxicity does not fade when the plant dries, so clippings on a compost heap, fallen leaves and even the water from a vase of cut stems remain dangerous. Smoke from burning oleander is toxic to inhale, for people as well as pets. There is no safe exposure to any part of this plant.
What happens if a dog eats too much?
Drooling, vomiting and diarrhoea come first, often within a few hours. What follows is the serious part: the cardiac glycosides disturb the heart's rhythm, producing weakness, a slow or irregular heartbeat, cold extremities, collapse and, in severe cases, cardiac arrest. Tremors and dilated pupils may appear too. Because the heart effects can develop while the animal still looks only mildly unwell, a normal-seeming pet after chewing oleander is not reassuring.
⚠ What to do if your dog ate oleander
Treat any suspected ingestion as an emergency and go in immediately (ASPCA 888-426-4435 · Pet Poison Helpline 855-764-7661 from the car). Take a piece of the plant or a clear photo — oleander is often confused with other shrubs, and confirming it changes everything. Pets need cardiac monitoring, and there is a specific treatment (digoxin-specific antibody fragments) available for severe cases. Outcomes depend heavily on how quickly the heart is being watched.
⚠️ Worried your pet got into this?
Frequently asked questions
Are dried leaves less dangerous?
No — the toxins are stable when the plant dries, which is why garden clippings and fallen leaves cause a lot of cases.
Should I remove oleander if I have pets?
If your pet has access to it and shows any interest in chewing plants, yes. At minimum, fence it off completely and clear fallen leaves.
More plants for dogs
By the CanMyPet Editorial Team · Reviewed against ASPCA Animal Poison Control, the American Kennel Club (AKC) and Pet Poison Helpline · Last updated July 31, 2026.
Sources
- ASPCA — People Foods to Avoid Feeding Your Pets
- American Kennel Club — Dog Nutrition
- Pet Poison Helpline — Poison List