What can cause mild gastrointestinal upset in a cat, regardless of a plant's official toxicity rating?

Answer

Sudden ingestion of any greenery due to the foreign material

Even if a plant is listed as non-toxic, the sudden ingestion of any greenery can cause mild gastrointestinal upset like vomiting or diarrhea simply because it is a foreign material.

What can cause mild gastrointestinal upset in a cat, regardless of a plant's official toxicity rating?
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