From a botanical perspective, the term "lily" specifically refers to plants within the genus Lilium (true lilies) and the genus Hemerocallis (daylilies). It is crucial for pet owners to understand this classification because many plants with "lily" in their common name are not true lilies and may have different toxicity profiles. For example, the Peace Lily (Spathiphyllum spp.) is not a true lily but belongs to the Araceae family, and while it can cause oral irritation, it does not cause the same acute, fatal kidney failure as true lilies.
The exact toxin in lilies (Lilium and Hemerocallis species) has not been definitively identified, but its effect on cats is well-documented and devastating. The entire plant—petals, leaves, stem, pollen, and even the water in the vase—contains the water-soluble toxin. Pollen is particularly hazardous as it can be groomed off a cat's fur after brushing against a flower, leading to ingestion. The toxin is rapidly absorbed and targets the kidneys, causing severe acute kidney injury (AKI) and potentially complete renal failure within a very short period, often 24 to 72 hours after ingestion.
Pet owners should be able to identify and avoid bringing these highly toxic plants into a home with cats. Dangerous species include, but are not limited to: the Easter Lily (Lilium longiflorum), Tiger Lily (Lilium lancifolium), Asiatic Lily (various Lilium hybrids), Japanese Show Lily (Lilium speciosum), Rubrum Lily (Lilium speciosum var. rubrum), Stargazer Lily (Lilium 'Stargazer'), and all parts of the Daylily (Hemerocallis species). The level of toxicity is extreme; ingestion of even one or two leaves or petals, or a small amount of pollen, can be a lethal dose for a cat.
As mentioned, not all "lilies" pose the same threat. The Peace Lily (Spathiphyllum) contains insoluble calcium oxalate crystals, which cause immediate mouth and throat irritation, drooling, and difficulty swallowing, but not kidney failure. The Peruvian Lily (Alstroemeria spp.) can cause mild gastrointestinal upset like vomiting and diarrhea but is not associated with the life-threatening nephrotoxicity of true lilies. However, any plant material can cause stomach upset or an unexpected reaction, so caution is always advised.
