Which plants are deadly (not just toxic) to cats?

August 27, 2021 12:03 AM

Short and sweet, yet hard to Google: Which plants are potentially deadly, not merely toxic, to cats?

I share my home with a very picky cat who has never shown any interest whatsoever in eating plants or flowers (or human food, or even tuna flake cat treats... this cat is a weirdo). But just in case, I'd like to know which plants or flowers might be *deadly* to my cat? I'll brave the risk of an upset stomach or diarrhea since she's so unlikely to eat them in the first place, but I could never forgive myself if I poisoned her seriously through laissez-faire.

I know to avoid lilies, wondering if there are other particular plants to keep out of my home.

posted by serelliya to Home & Garden (7 answers total)

Best answer: LD50 for a lot of these plants haven't been established. The only reason I know this is because I knew someone I knew was a bit of an odd duck and thought marijuana could kill their cat so I had to look it up. Marijuana is listed on nearly every list of toxic plants yet the LD50 is not known and only one death attributed to ingestion of marijuana by a cat... ever... with possible other substances being the cause (ASPCA). In my opinion if the LD50 for a substance has not been established it can't really be considered lethal.

The ASPCA toxic plant list for cats is your best bet but note that anything that's been attributed to poisoning a cat is on that list. Similarly the Merck Vet Manual on Poisonous Houseplants and Ornamentals is a lot more narrow but doesn't rank it by toxicity. A simple limiting of the list by searching for "death" where it isn't followed by "is rare" and making sure death is either not specified by species or isn't just non-felines renders this list:

- Autumn crocus
- Rhododendron
- Lily-of-the-valley
- Marijuana* (disagrees with above ASPCA but doesn't cite cases or provide an LD50)
- Mistletoe
- Yew (very lethal)

As you can see that's a pretty small list and I doubt there's been actual formal studies on these. It seems like if it is lethal to humans and mice, it gets on the list. I would trust Merck Vet Manual and ASPCA as pretty reliable even with the weird marijuana thing. But given the large number of cats, our extensive history living with them we'd know at this point if things were incredibly lethal to them and not on that list.
posted by geoff. at 1:01 AM on August 27, 2021

Note that for mistletoe, it's the berries that are poisonous. My cats have played with dried mistletoe leaves (not by my leave) and possibly chewed them without ill effect.
posted by I claim sanctuary at 2:48 AM on August 27, 2021

I had never before heard that cannabis in plant form was attractive to cats or fatally toxic for cats to ingest, and as I am a grower with a cat, that perked me right up.

It appears to be nonsense. Here’s a reasonably rational discussion that asserts the LD of cannabis plant matter is “15 grams per pound of body weight.” So my zaftig tuxedo girl would need to eat 165 grams, or more than a third of a pound (never mind the economic cost of that!) of cannabis plant matter to kill herself, if that’s true. (She’s never shown any interest in said plant matter, and for that matter she is unmoved by catnip too, which I grow in some abundance both inside and outside my house — there is NO better bee attractant!). And while bunny has an appetite, hence her 11 pounds of butterballness, the idea that she would ever consider consuming more than a few grams of any solid substance in any one sitting is laughable. Except maybe greenies.

I found quite a few assertions that cannabis “is toxic to cats” online, but not a single shred of scientific rationale for that statement, anywhere. Nor did I find any anecdotes of cats suffering ill effects from ingesting the raw plant. Nor in my wide circle of friends who grow serious quantities in their home grows and have beloved cats (the Venn diagram is awfully close to a circle, in fact) am I aware of anyone who takes this risk seriously or has any negative anecdotal experiences. Indeed as I also have grown outdoors, I can say that very few animal pests are an issue for cannabis in places I’ve grown. Bugs and fungi are another story. But I’ve never worried about deer or mice or bears or raccoons the way I do for other things I grow. Never even think about it. So unless I’m totally ill informed, I seriously doubt that having cannabis plants in your home or garden places your cats at any particular serious risk.

I’d love someone to show me the real science that says otherwise. Because otherwise this sounds like (metafilter:) the feline version of reefer madness.

Obviously cannabis smoke, vapor, edibles, or oil would not be good things for cats to ingest. My girl tends to leave the room.
posted by spitbull at 6:53 AM on August 27, 2021 [1 favorite]

Best answer: Some of the plants on this list specifically mention causing death if ingested by cats.
posted by Martha My Dear Prudence at 9:06 AM on August 27, 2021

Best answer: I have a few supposedly toxic plants in my house like monstera and fiddle leaf fig since my kitty isn’t usually too interested in eating plants, but based on my reading, I would never risk keeping cycads/sago palms or lilies. My cat once managed to get past me into a room where we had been keeping a bouquet of lilies someone had sent behind closed doors, and got some pollen on her fur—I ended up shaving that patch of fur because I couldn’t get the last orange pollen stain out and was so worried she’d end up licking it clean and end up dying, apparently even a few grains of pollen can do it.
posted by music for skeletons at 9:18 AM on August 27, 2021 [1 favorite]

Best answer: Not exactly a house plant, but recently I had been growing some green onions on my countertop, where normally my cat doesn't bother to go. I'd also assumed that, being an occasionally sensible beast, he wouldn't have any interested in them. Well, of course he had a nibble, so I looked it up and discovered that alliums are apparently all very, very poisonous to cats, though not in the traditional way: The organosulfoxides cause problems with their red blood cells (link to a PDF), such that hours or days later they get anemic and there isn't a lot that can be done to treat it. The prognosis depends on on how much they've eaten.

Luckily, the foolish boy already has a sensitive stomach on a good day, so it came right back up. Of course, I'm not growing onions in the window anymore.
posted by past unusual at 9:38 AM on August 27, 2021

One of my cats almost died this year after munching on a croton.
posted by Jess the Mess at 5:27 PM on August 29, 2021