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My 6 kg cat ate a piece of pepperoni pizza that was left in the box on the counter overnight — is the spoilage or the garlic powder the bigger concern?

Cats · Food safety

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

Short answer

The spoilage is the more immediate concern. Overnight, bacteria like staphylococcus can multiply on the fatty cheese and meat, potentially causing vomiting and diarrhea within a few hours. The garlic powder is a longer-term toxin that can cause anemia if eaten repeatedly, but one old slice likely doesn't contain a dangerous single dose. Watch for signs of food poisoning: lethargy, vomiting, or a tender belly. Offer bland food like plain chicken if she'll eat, and call your vet if she seems unusually quiet or can't keep water down.

Pizza — Food safety facts

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

The dough, cheese and sauce bring salt, fat and usually onion and garlic powder.

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

Pizza 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.

A heavy salt load drives up thirst and urination, and in the worst cases leads to sodium ion poisoning, which is a genuine emergency.

Rich, fatty food is the classic trigger for pancreatitis, a painful inflammation of the pancreas that usually needs veterinary treatment rather than rest alone.

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

Pizza 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 Pizza food facts page.

Open the full food page: Pizza food facts →