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Common Feline Toxins Part 1

Common Feline Toxins Part 1
by Dr Caity Venniker

Read time: 6 min

Don't let Curiosity Kill the Cat

There are many common household items which can be toxic to cats. Today we discuss some of the most relevant toxins found in human food and medication. In Part 2, we will look at some of those found in plants, pet products and household chemicals.

Dogs are generally much greedier than their feline siblings, and more inclined to gobble up substances that they shouldn’t (the list of dangerous items for canines would be a lot longer and more creative - it may include stones from the park; delicious nappy from the rubbish; your favourite slippers...).

Cats, while being a bit more discerning in their taste, have other factors which put them at risk:

  • Their small size means that even a tiny dose of a toxic substance can be harmful.

  • They are deficient in certain enzymes relative to other species which prolongs and exacerbates the effects of some drugs

  • As dedicated self-groomers, they often ingest toxins through this process.

  • They tend to be very private and so the first hint that a toxin has been ingested may be when the cat is already ill.

Many cases of intoxication have to be treated on suspicion, based on clinical signs and a history of what the cat may have been exposed to within its environment.

Symptoms differ widely according to what physiological system is affected. Signs to look out for include vomiting; salivation; diarrhoea; muscle tremors; in-coordination and seizures; difficulty breathing; weight loss; pale or brown tinged gums and increased thirst among others. If you have even a small concern that your cat may have been poisoned, it is important to go to the vet immediately. With most poisons, it is imperative that treatment is started as soon as possible, ideally before clinical signs become apparent.

There are unfortunately many household items which are toxic to cats. Today we take a look at those most commonly found in certain human foods and medications.

Common Toxicities From Human Food

Garlic, Onion, Chives and Leeks

Cats are more sensitive to this group than other species and even just five grams of onion per kilogram (DVM 360, 2015); or a single clove of garlic (Pet Health Zone, 2020) can result in toxicity.

The most common signs are vomiting, diarrhoea and lethargy; which can be followed by pale or brown-tinged gums two to five days later, and sometimes difficulty breathing, among other symptoms.

This group of toxins causes damage to red blood cells in cats and this can also lead to kidney injury. It is important to be aware that this group of ingredients is often present in baby food, as well as dips, sauces and soups - which may be more tempting to your pet than the raw vegetable form.


The next time you are leaving the house and envy your cat still snuggled up in the warm folds of the duvet, remember this sad fact: In every one of those luxurious nine lives, chocolate is forbidden. Feel better? It’s a pleasure.

Chocolate contains two substances which are toxic to cats: theobromine and caffeine. The amounts of these vary considerably between different types of chocolate, with white chocolate being much safer (Cortinovis & Caloni, 2016), and dark or baking chocolate the most dangerous.

Even tiny amounts can result in toxicity, so no amount of chocolate should ever be given to your cat. This applies to anything that contains cocoa, including chocolate puddings, cakes or hot chocolate. The first signs include vomiting, diarrhoea and restlessness, which can progress to seizures and death.

Raisins and Grapes

The exact mechanism of grape toxicity is not understood; and is more apparent and well recorded in dogs than in cats.

For this reason, the toxic dosage for cats is currently unknown, but any variations of the fruit should still be treated with caution as a potential cause of kidney damage.

Are there other potential toxins I should be careful with?

Other potential toxins from human food include alcohol and yeast dough; and to a lesser degree green

tomatoes. Interestingly, xylitol (a popular sweetener) is currently believed to be much less toxic in cats than in dogs (Nicholas, 2018) but should still be treated with caution.

Common Toxicities From Human Medications

Never assume that human medications are suitable for pets, as a high percentage of cases of animal toxicity are through the consumption of drugs intended for human use.

Even if the drug is appropriate for animal use, the dose is often very different. This is because not only is there a significant size difference between humans and cats, but also often a different way and rate of metabolising the drug.

Always consult with your veterinarian before giving any medication to your pet that has not been prescribed specifically for him or her.

Paracetamol/Acetaminophen (Tylenol)

Paracetamol is one of the most common toxicities in cats.

Possibly the high incidence of cases results from the fact that it is sometimes used in dogs (again, always consult with your veterinarian first as it cannot be used long term or in dogs with liver problems). In contrast, cats have much lower levels of the enzyme needed to metabolise it, and so are extremely sensitive to toxicity. The toxic dose is only 50mg/kg (Cannon, 2013).

Paracetamol causes changes to red blood cells which can lead to anaemia and liver failure. The first signs include lethargy, weakness and vomiting; followed shortly by pale gums with a blue or brown tinge. The dangerous effects of paracetamol toxicity happen very quickly and the prognosis for recovery is guarded, so it is imperative to take your cat to the vet for treatment as soon as possible.

Non-Steroidal Anti-Inflammatories (Ibuprofen, Aspirin etc.)

The use of non-steroidal anti-inflammatories is another common cause of feline toxicity. Even those intended for use in cats, if given incorrectly can be harmful (this includes not only ensuring the correct dose and whether it should be given with food, but also the health status of the cat being treated, and possible interactions with other medications).

Those intended for humans and dogs are more dangerous as there are species differences in the way the drugs are metabolised. Even topical versions can be a problem, so always wash your hands after applying any medicated creams to yourself; and be aware of the risk of your cat rubbing against you.

The major adverse effects of non-steroidal anti-inflammatories result from stomach ulceration and kidney damage. Symptoms include inappetence, vomiting, abdominal pain and lethargy.


Unlike paracetamol and non-steroidal anti-inflammatory toxicities, which usually result from owners mistakenly dosing their pets; antidepressant toxicity more frequently occurs after cats have voluntarily eaten them.

Many cats are drawn to the smell or taste of certain antidepressants (Lee,2012). Signs vary according to the type of antidepressant ingested, but include lethargy, vomiting, lack of coordination, seizures and coma. Symptoms appear quickly after ingestion (from 30 minutes to a few hours) and can progress rapidly.

Selective Serotonin Reuptake Inhibitors are much less likely to be fatal than Tricyclic Antidepressants or Monoamine Oxidase Inhibitors (Wismer, 2006), but all cases should be treated as an emergency requiring prompt veterinary attention.

Other Potential Toxins from human medications

Other dangerous human medications include treatments for ADHD, cancer and diabetes; as well as diet pills and muscle relaxants.

Any human medication, even homeopathic treatments, should always be checked for safety by a vet before giving them to your cat.

How vets treat toxicities in cats

Toxicities in cats are veterinary emergencies, even if no symptoms are yet present.

If your cat has eaten medication it is very helpful to take the box with you to the vet so that they can see the exact ingredients and dose; and treat accordingly.

Veterinary treatment may involve making your cat vomit. This depends on the time that has elapsed since eating the toxin as well as which toxin is being treated. It also may include performing gastric lavage; feeding a special type of medicinal charcoal to help absorb the toxin; giving intravenous fluids or an antidote if one is available; and supportive care for any symptoms.

As always, prevention is better than cure, so being mindful of toxins within the home environment is the best way to avoid any problems. Curiosity may kill the cat, but not if vigilance gets there first!

In Part 2 we will discuss more common feline toxicities found in the home, focusing on plants, pet products and chemical hazards.

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  1. (2015, August 1). “A Pungent Poisoning: Onion Toxicosis in a Cat” DVM360. Retrieved from: on 31 January 2020.

  2. Cannon, M. (2013). Toxins – Common Feline Poisonings. In BSAVA Manual of Feline Practice (pp. 138-141). Gloucester, UK: British Small Animal Veterinary Association.

  3. Cortinovis, C. & Caloni, F. (2016, March 22). Household Food Items Toxic to Dogs and Cats. Frontiers in Veterinary Science. Retrieved from: https://www/ on 31 January 2020.

  4. “Garlic Toxicity and Pets.” Pet Health Zone. Retrieved from: on 31 January 2020.

  5. Lee, J. (2012). “The Top 5 Cat Toxins”. Pet Health Network. Retrieved from: on 2 February 2020.

  6. Nicholas, J. (2018, July 19). “Is Xylitol Toxic to Cats?”. Preventive Vet. Retrieved from: on 1 February 2020.

  7. Wismer, T. (2006). Antidepressant Drug Overdoses. In Veterinary Technician (pp. 278-281). Retrieved from:>files on 2 February 2020

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