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One of my two 5 kg cats licked a big smear of pesto off a pasta plate, but the other didn't — do I need to monitor them both, or just the one who ate it?

Cats · Food safety

Last reviewed: 2026-09-05 · Reference ranges: ASPCA, Pet Poison Helpline & Merck Veterinary Manual

Short answer

Focus on the cat who ate it, but keep the pesto away from both. The garlic in pesto is toxic, and a big lick could cause drooling, stomach upset, or red gums in the next few hours. Watch specifically for her pawing at her mouth or hiding. The other cat is only at risk if she also gets into it, so clean all plates thoroughly and put the pesto jar where neither can reach. There's no need to separate them unless the affected cat starts vomiting repeatedly and you need to keep the mess contained.

Pesto — Food safety facts

Feed with care · Cats · full breakdown on the linked food page

Built on garlic, which is toxic to dogs and cats, plus pine nuts and cheese.

Dogs and cats carry the same rating (Feed with care), so the notes below hold for either pet.

Pesto is not poisonous to cats, but it is easy to over-feed. Rich fat, salt or seasoning can bring on vomiting or diarrhoea within a day, and repeated large portions are a recognised trigger for pancreatitis.

If it ate some before you noticed, watch for vomiting, diarrhoea, loss of appetite, unusual tiredness or a painful, swollen abdomen over the next 24 hours. A one-off small amount in a healthy adult usually passes with water and rest; repeated exposure, a puppy or kitten, a senior, or a pet with an ongoing illness is a reason to call your vet the same day.

Why these cautions matter

Garlic and onion damage a pet's red blood cells and can bring on anaemia. Signs are often delayed for several days, so looking fine straight afterwards does not rule it out.

Most adult pets make very little lactase, so dairy tends to produce gas, bloating and diarrhoea instead of usable nutrition.

Pesto can turn up now and then, but not as a daily habit: keep the rest of the day's food unchanged and watch the litter box and how quickly they finish the next meal.

The full verdict, portion guidance and serving notes are collected on the Pesto food facts page.

Open the full food page: Pesto food facts →