Disinfectant case studies

Case 1

Figure 1: Drooling and redness and ulceration of the tongue 12 hours after licking a patio treated with a cleaner containing benzalkonium chloride. From Bates and Edwards (2014).1

As the weather improves we may look out at the patio and decide it is in need of a clean up to remove the greenish tinges and dirt collected over the winter. Many patio cleaning products are available for this purpose but many contain benzalkonium chloride, a chemical that can be toxic to cats.

One owner learnt this the hard way when their three year old cat became unwell 12 hours after the patio had been cleaned. The owners had kept their cat off the patio until the cleaning product had dried (as per the instructions). However after she developed a high temperature, drooling and ulceration in her mouth (figure 1) it was assumed she had licked the dry product left on the patio or licked her feet after walking on the patio after it had been cleaned. The cat was treated with pain relief, fluids and she was fed soft food only. After 6 days she had fully recovered but her owners remember it as a frightening time and in future will completely rinse the patio after cleaning before allowing it to dry and only then allowing their cat to walk across it.

Case 2 

In this second case the owners saw their cat rolling on a wet pavement outside their house 2-3 hours after it had been cleaned but thought nothing of it as they were unaware of the danger of some disinfectants and had no idea that the product they had used contained benzalkonium chloride. It wasn’t until some 18 hours later when the cat refused food and seemed depressed that they took him to their veterinary clinic to be checked over. There the vet noted the cat was dehydrated and had severe oral ulceration and swollen paws and asked the owners about exposure to chemicals. The owners felt terrible that they hadn’t connect the pavement cleaning with the cat’s illness but thankfully he responded well to treatment with fluid therapy to rehydrate him as well as pain relief and medication to protect his stomach from the effects of the chemicals. He needed help eating for a few days as the oral ulcers healed but went on to make a full recovery. This case shows how owner awareness of potential toxicity can lead to earlier veterinary treatment and a quicker recovery.

Case 3

Figure 2: Another cat who encountered benzalkonium chloride disinfectant showing ulcerated tongue 2 days after exposure to the disinfectant. From Bates and Edwards (2014).1 

Not all disinfectant poisoning occurs outside. Cats are curious creatures and when a nosy little cat went into the bathroom and the owner heard a crash they thought little of it as she was always knocking bottles off the bathroom windowsill. This time though it wasn’t shampoo it was concentrated disinfectant and with a lose lid the contents spilled onto the floor and the cat walked through the puddle of chemicals.  Being fastidiously clean creatures she soon washed the disinfectant off her feet but in the process ingested some which contain benzalkonium chloride. Immediately after cleaning herself she started to drool and by 12 hours after exposure she had developed ulcers in her mouth (figure 2) and sore areas on her legs and feet became apparent after 3 days. She was rushed to the vets and treated with pain killers and medication to protect her stomach and to prevent her vomiting as she looked very nauseous. The mouth ulcers were so severe she needed a feeding tube to provide food as she was too painful to eat despite the pain medication. The skin lesions took a few days to heal up but by 10 days after exposure to the disinfectant she had started to eat by herself and was back to her normal nosy self. This time however her owners will make sure the top is screwed onto the disinfectant bottle, and safer still they will lock it away in a cupboard away from curious cats!


  1. Bates N, Edwards N. Benzalkonium chloride exposure in cats: a retrospective analysis of 245 cases reported to the Veterinary Poisons Information Service (VPIS). Vet Rec 2015; 176: 229.

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