Is Oleander Toxic to Dogs?

Oleander (Nerium oleander) is one of the most commonly planted shrubs in Central and South Texas highway medians and home landscapes, and it is severely toxic to dogs, cats, and horses. The ASPCA Animal Poison Control Center plant database flags every part of the plant: leaves, flowers, bark, roots, and even the water in a vase that has held cut Oleander stems. The Merck Veterinary Manual classifies the toxic compounds (cardiac glycosides, primarily oleandrin) in the same category as digitalis.

Symptoms of Oleander ingestion in dogs: drooling, vomiting (often bloody), abnormal heart rhythm, weakness, and cardiac arrest in severe cases. Symptoms can appear within hours. As few as a handful of leaves can be lethal to a medium dog. If your dog has eaten any part of an Oleander, call the ASPCA Animal Poison Control Center at (888) 426-4435 immediately. This is a true emergency.

Oleander is not native to Texas. It is widely planted because it is drought-tough, blooms all summer, and tolerates poor soil and salt spray. You will see it lining I-10 between Houston and San Antonio, in median strips throughout the Rio Grande Valley, and in HOA front yards across South Texas.

Safe native alternative: Desert Willow (Chilopsis linearis). Showy pink and purple trumpet flowers from June through September, drought-tolerant, attracts hummingbirds, and is not on the ASPCA toxic plant list. Grows in Zones 7 through 11. If you currently have Oleander and pets, removal is the only safe path; even composted Oleander remains toxic, so bag and bin the debris.