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Curiosity Poisons the Cat: Common Toxicities in our Cats

Oscar, a magnificent 6-year-old Birman, arrived at the clinic at Easter, with a sudden onset of vomiting, drooling, increased thirst, and a refusal to eat … even when offered his favourite creamy treats. He had also lost weight. 

Just a month earlier, he’d had normal blood results at his annual check, and was on the portly side, being a cat who appreciated the ‘finer things in life’: both his food, and that of his humans. Blood tests showed that Oscar was in irreversible kidney failure and the tragic decision was made to put him to sleep, as his residual kidney function continued to plummet.

What could possibly have caused this? You may have guessed it … lilies.

Oscar’s family had been gifted a seasonal bouquet, containing Easter lilies. Cats are exquisitely sensitive to toxicity from all flowers in the lily family. Lilies cause kidney failure in as little as 12-36 hours. Oscar, being a cat, was particularly curious about anything new in the house. He may have gotten the pollen on his fur, inhaling, grooming, and licking it off; he may have chewed tentatively on a stem; or, given cats like to drink from all places but their water bowls, he may have lapped at water droplets on the flowers, or in the vase.
All parts of all lilies can kill cats.
We adore our feline companions, admiring their independence, inquisitive personalities, and agility. Unfortunately, these very traits can sometimes lead them into danger. Seemingly innocuous substances can be lethal to our cats – so, to keep them safe, it’s critical to understand the common, and not so common, toxicities they may encounter.

Flowers and houseplants are so delightful for us to have around the home and cats also take delight in plants! Many indoor and outdoor plants are toxic to cats, however. To be safe, research all plants before you adding them your home or garden.

Arya: "What is this? Can I eat it?"
Common flowering plants of concern include every kind of lily, daffodils, oleander, bird of paradise flowers, azaleas, gladiolas, irises, hyacinths, rhododendrons, sago palm, tulips, narcissus, hydrangeas, dieffenbachia, cyclamens, elephant ears and poinsettias. 

Ferns, such as the emerald, asparagus, plumosa and lace varieties may also be toxic.

Other toxic indoor plants include aglaonema, the arrowhead vine and any plant in the dracaena family. Aloe vera and multiple cactus species, anthurium, hellebore, morning glory, nightshade, pussy’s ears, and mother-in-law’s tongue are toxic.

Happily, many gorgeous native Australian plants, including grevillea and banksia, are perfectly safe for cats, or are toxic only if eaten in very large quantities. 

Exceptions include kangaroo paw, flannel flower, Macadamia trees, certain types of eucalypts, and the Lantana bush. See here for a comprehensive list of common toxic indoor plants in Australia.

Many of us have herb gardens and these are best kept out of reach too. The important caveat here is that cats generally avoid herbs and, unlike lilies, they must be consumed in large quantities to be dangerous. 

Toxic herbs include oregano, marjoram, cocoa, epazote, tarragon, chives and scallions, bay leaf, borage, sorrel, chamomile, lemon verbena and lemongrass, lavender, and mint. Catnip hails from the mint family and is toxic when ingested in large amounts!

Cannabis use is growing with legalisation across much of the globe. Most cannabis (marijuana) toxicity in cats is due to inhalation of second-hand smoke or vapour, rather than ingestion of the cannabis plant. If you suspect your cat has become unwell due to exposure to illegal substances, please do tell your vet. You will not be reported to the police, and we can treat patients more effectively.

Given the laundry list of toxic plants, it’s unsurprising that many plant-derived essential oils are a no-go for cat families. A list of toxic oils can be found here. Essential oils may be absorbed through the skin via direct contact, or cats may ingest oil through grooming, or inhale vaporised oils. In cats with underlying respiratory disease, such as asthma, inhalation is particularly dangerous.

Permethrin toxicity is one of the most common we see in cats. This insecticide is present in numerous household and garden sprays, and in moth balls. However, the number one reason for toxicity is when pet parents accidentally use permethrin-containing flea or tick collars on their cats, or spot-on treatments intended only for dogs. Permethrin causes neurological signs such as tremors, seizures (or fits), blindness, abnormal ‘drunken’ walking and is a serious medical emergency.

Accidental poisoning with human medicines, or too large a dose of cat medicines, are common toxicities. The common painkiller paracetamol, or ‘Panadol’ (acetaminophen in the USA), is a killer. Cats lack the liver enzymes to metabolise this drug and a single tablet is enough to kill, in hours. Paracetamol reduces the blood’s ability to carry oxygen and poisoned cats are weak, with rapid breathing, vomiting, or drooling, and even with treatment, they can suffer fatal liver damage.

Other human painkillers such as aspirin or ibuprofen (e.g., ‘Nurofen’) are toxic for the kidneys, and cause stomach ulcers. Whilst rare, poisonings with other human drugs such as antidepressants and ADHD medications, have been documented.

Recently I treated a lovely tortoiseshell who had accidentally been given a 10-fold overdose of her medication, Meloxicam (a medication like ibuprofen). In high doses and cats with health issues, Meloxicam may cause severe kidney damage, stomach ulcers and sometimes death. Getting a drug dose wrong, by a decimal place, is so easy to do! We must be vigilant with all medication doses.

Rodent (mouse and rat) bait is a common cause of poisoning in cats and is often termed a ‘secondary poisoning’. Cats are generally exposed after they snack on a sick or dead poisoned rodent or rarely, wildlife such as possums. Cats may eat the bait itself, as well. Dying rodents may go enter a yard in daylight or come indoors, seeking warmth and water, meaning that cats in rat-bait free households and yards may still be vulnerable.

The most common rodent bait is an anticoagulant, including products Ratsak® or Talon®, which causes uncontrolled haemorrhage or bleeding, up to 4 days after exposure. Cats may have blood in their urine, or bleeding from the nose, mouth, or anus, though most often, bleeding is internal, and cats simply collapse. The treatment is Vitamin K, and sometimes blood transfusions to replenish lost blood. The RSPCA provides information on safer and more humane rodent management here.

Snail bait rarely causes toxicity in cats that are curious enough to eat bait in the garden, or less commonly, get powder or liquid forms of toxin on their coats. 
In all cases, emergency veterinary treatment is required and more information can be found here and here.

Given our climate, we don’t often use antifreeze (ethylene glycol) in Australia, and again, it’s very much a poisoning we see in dogs. 

This is likely due to cats lacking the taste receptors for sweetness, the appeal of antifreeze being that it is super-sweet. However, just one inquisitive lick is all that is required to cause fatal kidney failure. (Predictable, and horribly, the sweetness renders antifreeze a significant risk for small children). Antifreeze leaks from cars must be addressed immediately.

Household cleaners and bleach can cause eye and lung irritation and chemical burns from direct contact.

Foods Toxic to Cats

Cats are the most sensitive of all species to toxicity from onionsgarlicchives, and leeks. Toxicity occurs with both fresh, raw produce and food containing dehydrated flakes or powders, and dry onion soup mixes. There are reports of fatalities following ingestion of less than a teaspoon of cooked onions. One of my patients developed bloody urine after a teaspoon of onion. These foods cause a life-threatening anaemia, often requiring emergency blood transfusions.

Grapes and raisins may cause serious illness in cats and the doses don’t need to be high. A single raisin or sultana may be enough to cause vomiting and drooling in around 15% of cats (and dogs), and this can progress to fatal kidney failure.

Artificial sweetener, xylitol, found in some lollies, protein bars, toothpaste etc, are very toxic to the feline nervous system and kidneys, though are, again, more of a dog problem, given cats’ lack of a sweet tooth.

Caffeine, alcohol, high levels of cocoa (such as those in cooking chocolate) are toxic, though are rarely ingested by cats. This said, I have seen some cheeky Burmese kittens become quite ill after feasting on dark chocolate. Burmese are truly the Labradors of the cat world. Never say never, with cats!

Creepy Crawlies…

Arthur, a domestic shorthair received a fatal envenomation snake bite from an Eastern Brown Snake trying to protect two children in the back garden of his family's home on the Sunshine Coast 
(Animal Emergency Service Facebook)

Australia is famously home to many venomous critters. Bites from the Eastern Brown Snake, Tiger Snake, and Death Adder can all be fatal without immediate veterinary treatment.

Fascinating research has revealed though, that cats are twice as likely to survive snake bite than dogs as the venom has a more potent effect on canine blood, and cats are more likely to be bitten on a paw, whereas dogs, on the face, where there are more blood vessels and faster absorption of venom. Cats may be more likely to be bitten however, given their curious natures.

Spider bites generally cause localised pain, swelling and wounds, however, rarely, some cats may develop neurological signs and breathing difficulties (like tick paralysis). Spiders of concern include the Funnel-Web, Redback, White-tail and Australian Tarantula species. Contact your vet if you find such a spider near your cat, or they show signs of a bite.

The cane toad secretes a toxin, potentially lethal to cats. Even indirect contact, such as drinking from a water source where a toad has been, can be dangerous.

Finally, due to their grooming habits, anything on a cat's paw or fur could potentially be ingested. Cats have unique metabolic pathways, rendering them sensitive to many substances. General signs of poisoning may include lethargy or being ‘off-colour’, drooling, vomiting, diarrhoea, abnormal ‘drunken’ or wobbly movement, rapid breathing (with an open mouth), bleeding from the mouth, nose, anus or bladder, lack of bowel or bladder control and collapse.

If your cat shows any of these signs or similar ones; if you see them ingest a toxin; and even if you’re unsure, contact your vet. Emergency instructions may be found online.

Read on for further information, and the Australian Animal Poisons Helpline provides free advice 9am-5pm AEST, 7 days a week, and for $75AUD after hours. (Call 1300 TOX PET in Australia).

written by Dr Bec, August 2023 for Australian Cat Lover (all rights reserved).

About our writer

Dr Bec is a Melbourne-based veterinarian and academic, working in the clinic, animal welfare, the media and medical research. She has a passion for sharing fascinating facts and the latest research on the intriguing lives and science of all animals, particularly those we share our lives with.

Dr Bec is a regular guest on Melbourne radio, a columnist for Australian Dog Lover Magazine, Australian Cat Lover Magazine, and Pet Insurance Australia, and she presents short segments on all things animal related (see Insta and Facebook). Her emphasis is on sharing of evidence-based veterinary advances and the empowerment of pet parents, and society, through promoting medical literacy, or the understanding of our pets’ health, and our own. She relishes reaching out to all animal loving audiences.

Her academic and clinical research spans several areas, with a focus on the role of the microbiome in pet health, preventative medicine, developing new veterinary medicines, clinical trials that benefit animals and humans, and working to prevent antibiotic resistance.

Dr Bec advocates for animal charities that promote animal welfare, in Australia and overseas.

Her blog can be found at: and she may be contacted at

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