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My 10-year-old cat who is already lactose-intolerant ate a small cube of cheddar mixed into her wet food — what should I expect?

Cats · Food safety

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

Short answer

Most likely loose stools or mild diarrhea, but it depends on how much she actually ate and how sensitive her gut is right now. A small cube of cheddar mixed into wet food is unlikely to cause severe illness in a 10-year-old cat, even one with known lactose intolerance. Watch for vomiting, excess gas, or softened stools over the next 12–24 hours. If she has never had cheese before, start with something even smaller next time or skip it entirely. Stop feeding cheese if you notice any diarrhea, and call your own vet if the loose stools persist beyond a day.

Cheese — Food safety facts

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

Most pets are lactose-intolerant to some degree. Tiny pieces are fine as treats; avoid if your pet gets diarrhoea.

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

Cheese 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

Added sugar brings empty calories, and over months that means weight gain and dental disease — both far harder to undo than to avoid.

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

Cheese 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 Cheese food facts page.

Open the full food page: Cheese food facts →