Are Hydrangea Plants Poisonous to Pets?

A blue hydrangea.

According to the Humane Society of the United States, "more than 700 plants have been identified" as poisonous to pets. Ingesting a poisonous plant, however, will not necessarily prove fatal. The hydrangea is among plants that are poisonous to pets.

Identification

Hydrangeas are shrubs that produce clusters of flowers in a range of colors, including white, pink and blue.

Chemistry

Hydrangeas contain cyanogenic glycosides, which---when ingested and combined with enzymes in the body---produce cyanide. That, in turn, can lead to cyanide poisoning.

Symptoms of Toxicity

According to the American Society for the Prevention of Cruelty to Animals, most pets will not consume enough of a hydrangea plant to cause cyanide poisoning. Some pets, however, may experience depression, vomiting and diarrhea after ingesting the plant.

References

• East Texas Gardening: Hydrangeas Brighten Landscape
• Humane Society of the United States: Plants Potentially Poisonous to Pets
• University of Pennsylvania School of Veterinary Medicine: Cyanide Containing Plants
• ASPCA: Hydrangea