Yes, peonies are poisonous to cats. The toxic component in peonies is called paeonol, which is found in all parts of the plant but is most concentrated in the roots and stems. Ingesting peonies can cause symptoms such as vomiting, diarrhea, lethargy, drooling, increased heart rate, respiratory distress, and allergic reactions in cats. While peony poisoning is usually not fatal, it can lead to dehydration and more severe symptoms if left untreated. Immediate veterinary attention is recommended if a cat is suspected of ingesting any part of a peony plant. To keep cats safe, it is advisable to keep peony plants out of their reach and to seek prompt veterinary care if ingestion occurs. Treatment may include inducing vomiting, administering activated charcoal, providing fluids, and supportive care depending on the severity of symptoms.