Plants that are toxic to dogs and cats

It can take just one leaf of the wrong plant to turn a lovely living room into a veterinary emergency room. And the danger is often invisible: a plant that is harmless to a dog can be fatal to a cat, and the first signs appear within a few hours.

You do not need to memorise hundreds of scientific names. We have selected the plants whose serious toxicity is best documented and that you may have in the living room, on the balcony or in the garden, grouped by the organ they attack and by the signs to watch for before it is too late.

In cats, every part of a true lily (Lilium) or a day lily (Hemerocallis) is toxic: flowers, leaves, stem and pollen. It is enough for a cat to lick pollen that has fallen on its coat. And a lily without pollen is not safe either.

The dose is tiny: according to International Cat Care, less than one leaf can be fatal. Signs appear between one and six hours later (excessive salivation, vomiting, loss of appetite, prostration) and it is the kidneys that suffer. Even if it survives, the cat may be left with permanent kidney damage.

And in dogs? A lily causes at most digestive upset, and only in large amounts; the ASPCA classes the Easter lily as non-toxic to this species.

Beware of confusing names. Despite the name, the peace lily (Spathiphyllum), the calla lily (Zantedeschia) and the lily of the valley (Convallaria) fall outside this group: they have other toxic effects, and International Cat Care does not consider them safe.

Beyond the lilies, the danger is shared: according to the ASPCA, all the plants that follow are toxic to both species. They are grouped by the organ they attack, and the signs given are those the ASPCA itself describes.

Not every toxic plant puts a life at risk. These, common indoors, irritate the mouth and stomach and, in the sources consulted, rarely cause more than that, just as any plant that is ingested can cause vomiting and diarrhoea. Knowing the difference avoids both unfounded alarm and carelessness.

When an ingestion happens, speed counts. These are the steps recommended by the PDSA, a British veterinary charity:

This list is neither exhaustive nor a ranking of plants by degree of danger: the ASPCA's database holds many others, and the fact that a plant is not listed here does not mean it is safe. Nor does it replace a vet: only whoever examines the animal can assess its condition.

The data come from organisations such as the ASPCA (American), International Cat Care and the PDSA (British) and from a 2020 European review, with cases from France, Italy, the UK, Sweden, Switzerland, Germany and Hungary. We found no Portuguese data or official sources. The review itself warns that these cases are little studied and probably under-diagnosed: the signs are non-specific, and neither owners nor vets know toxic plants well.