Are rhododendrons toxic to dogs?

Rhododendrons and azaleas belong to the same plant genus and share the same toxic compound, meaning the risk profile and the symptoms to watch for are essentially identical between the two, despite rhododendrons typically growing larger and looking quite different at maturity. If you know azaleas are a concern, rhododendrons deserve the same level of caution.

Rhododendrons are long-lived, slow-growing shrubs that were extremely popular in gardens planted several decades ago, meaning an older property can have mature, sprawling specimens that a new owner may not think to check for toxicity given how established and permanent they appear. Their evergreen leaves also mean the plant poses a year-round risk rather than only during a flowering season.

Drooling, vomiting, diarrhea, and weakness are the most common signs after a dog chews rhododendron leaves, with more significant amounts potentially affecting heart rate and blood pressure. Fallen leaves on the ground beneath a mature shrub remain toxic, so raking up debris around large specimens matters as much as managing the living plant itself.

Rather than removing a mature rhododendron, which can be a significant undertaking, fence off the base of the shrub or the section of border it occupies, and keep the area beneath it clear of fallen leaves and flowers. This is often more practical than full removal for an established, sprawling specimen, and a simple low barrier is usually enough since most dogs will not push through it to reach the leaves behind.