Why You Shouldn’t Let Your Cat Walk Across a Newly Cleaned Floor

Benzalkonium chloride, the culprit behind some tongue ulcers in cats, is commonly found in home furniture cleansers and disinfectants.

Toxic household cleaners spell trouble for pets. By: Fabian

Could a simple cleaning of your furniture harm your cat? Yes!

You may be surprised to learn that many common household disinfectants, patio cleaners and even hand soaps contain a chemical called benzalkonium chloride that is toxic to cats.

During a busy morning surgery, next on my list was Mitzie the cat, who had lost her appetite. Mitzie’s people were extremely concerned because Mitzie loves her food and out of the blue, she just stopped eating.

They had even tempted her with prawns, which were usually guaranteed to disappear as if by magic. On this occasion, she’d shown a brave interest but dropped the prawn out of her mouth. This was the final straw that triggered a panicky phone call to the clinic.

Physical Exam

Mitzie was a plump tortoiseshell cat who liked having her chin rubbed.

Given that she had no history of increased thirst or vomiting, no long-term weight loss and no fever, my list of likely differential diagnoses was rapidly shrinking. However, when examining a patient, I’m methodical, starting at the head and working down.

I had a quick look in Mitzie’s mouth, and a puzzle piece fell into place. The front third of her tongue was a livid red with one big, angry ulcer. That explained why Mitzie wasn’t eating; her tongue was too sore.

Next task: We needed to find out what had caused the ulcer.

Causes of Tongue Ulcers

Relatively few conditions cause tongue ulcers in cats:

  • One is cat flu, but Mitzie was fully vaccinated.
  • Another is kidney disease, but Mitzie had no other signs, such as weight loss or excessive thirst.
  • A third is licking a caustic substance.

I zeroed in on the caustic theory. Mitzie’s family looked at me blank-faced until I asked about patio cleaning. It turns out the spring weather had prompted them to clean the patio the previous weekend. This fit the timescale of Mitzie’s deterioration.

How Can a Patio Cleaner Cause a Sore Tongue?

When a cat walks across a wet patio and washes her paws afterward, the chemicals on her paws are transferred to her mouth, where they damage the tongue.

Cats are more discerning than dogs (when it comes to lapping disinfectant, at least) and rarely bite through containers, so most commonly they are poisoned as a result of fastidious cleaning of a contaminated coat.

The villain, benzalkonium chloride, is a common ingredient in many household disinfectants, household cleaners, hand washes and even ear and eye drops.

Tongue ulcers in cats are commonly attributed to toxic household cleansers containing benzalkonium chloride. By: trishhamme

Obviously, these cleaning solutions are not meant to be taken internally, hence the problem with cats cleaning themselves. The issue is made worse if the manufacturer’s directions are not followed and the patio cleaner is mixed incorrectly, resulting in too strong a mixture.

Safe Use of Common Disinfectants

Of course, disinfection is a good thing and to be encouraged. But a cat household must take special precautions. These include:

  • Read the label and mix the product as directed. Don’t be tempted to make it stronger.
  • Keep cats away from wet surfaces. Allow floors and worktops to dry completely before granting the cat access.
  • Keep cats away from recently cleaned patios. Wait for rain or hose down the previously dry patio to rinse it and make it safe before your cat goes out.

Other Methods of Disinfection

Consider steam cleaning household items when you feel like doing some spring cleaning. This is a no-chemical but highly effective way of dislodging dirt and killing bugs. Plus, once you buy the steam cleaner, the water is free.

If steam cleaning the kitchen floor isn’t an option, use diluted dishwashing liquid. It’s effective at freeing up dirt and isn’t toxic to your cat.

Treatment for Tongue Ulcers

In Mitzie’s case, the edges of the ulcer looked infected. I gave her an injection of long-acting antibiotic and some pain relief.

It is difficult for a cat with a sore tongue to lap, so Mitzie’s people took home a liquid diet to syringe into her mouth until things improved. Luckily, Mitzie wasn’t too badly affected, but some cats need intravenous fluids to prevent dehydration because their mouths are too sore even for syringe feeding.

Fortunately, Mitzie’s story has a happy ending. She did well and was back to eating prawns, much to her humans’ delight.


This pet health content was written by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS. It was last reviewed Dec. 17, 2018.