Ranunculus is a large genus of flowering plants in the family Ranunculaceae, comprising over 600 species, including buttercups, spearworts, and water crowfoots. The common garden variety, prized for its rose-like, multi-petaled blooms, is often *Ranunculus asiaticus*. From a botanical perspective, these plants have developed a defense mechanism against herbivores in the form of a toxic, irritant compound. When plant tissues are damaged—through chewing or crushing—an enzymatic process occurs that converts the non-irritating precursor compound, ranunculin, into a highly irritating chemical called protoanemonin.
The primary toxic agent in Ranunculus plants is protoanemonin. This compound is an oily, yellow lactone that is a potent vesicant, meaning it causes severe blistering and irritation upon contact with soft tissues. The concentration of protoanemonin can vary between species and even within the same plant, often being higher in the leaves and stems. It is most concentrated in the spring when the plant is growing and flowering. This toxin is the plant's primary chemical defense against being eaten by animals, effectively deterring grazing through its immediate and unpleasant effects.
When a cat or dog chews on or ingests any part of a Ranunculus plant, the released protoanemonin comes into direct contact with the mucous membranes of the mouth, gastrointestinal tract, and any other tissues it touches. This contact leads to intense local irritation. The effects are typically rapid and acute rather than a slow, systemic poisoning. Clinical signs of Ranunculus toxicity in pets can include excessive drooling (ptyalism), significant oral pain evidenced by pawing at the mouth, vomiting, diarrhea, and abdominal pain. If the sap comes into contact with the skin, it can cause redness, blistering (dermatitis), and swelling.
While the symptoms of Ranunculus poisoning are distressing and painful for the animal, the intoxication is rarely fatal if the amount ingested is small. This is because the immediate irritation and vomiting often prevent the animal from consuming a large quantity of the plant. The primary risks are related to the consequences of the gastrointestinal distress, such as dehydration from prolonged vomiting and diarrhea. However, in severe cases where a large amount is consumed, the irritation and inflammation can be more profound, potentially leading to significant difficulty swallowing or even more serious gastrointestinal damage.
