Why?
Pizza sauce almost always contains garlic, onion or seasoning powders, and these alliums damage a cat's red blood cells. Melted cheese, ham, pepperoni and sausage add lots of fat and salt, which can upset the stomach and even trigger pancreatitis. The baked crust isn't toxic, but it's just carbs a carnivore has no use for.
How much?
No amount of pizza is recommended, not even a small bite. Keep leftovers and boxes out of reach, since the smell of cheese draws many cats in.
The risks
- Anemia from garlic and onion, sometimes days later
- Vomiting and diarrhea
- Pancreatitis from the fat
- Too much salt: thirst and stomach upset
Your cat ate some: what now?
Call your vet without waiting for symptoms, especially if your cat ate toppings or sauce: garlic and onion damage can show up several days later. Tell them how much was eaten and what was on it, and don't try to make your cat vomit. A bare bit of crust is much less of a concern, but keep an eye on your cat for 48 hours.
Better options
If your cat wants to join in at dinner, offer a small piece of plain cooked chicken or beef, with no salt or sauce. A cat treat works just as well.
Common questions
Can cats eat pizza crust?
Plain crust isn't toxic, but it's salty, sometimes brushed with garlic oil, and gives your cat nothing useful. A nibble by accident is no big deal, just don't make it a habit.
Can cats eat pizza cheese?
A lick of melted cheese is usually harmless, though it's fatty and can cause diarrhea. The real danger is the sauce and toppings seasoned with garlic or onion.
This information is general and does not replace advice from a veterinarian. If your cat has swallowed something toxic, call your vet or an animal poison control center right away, without waiting for symptoms.