Why?
Spinach contains a lot of oxalic acid, which binds calcium and is passed in the urine. In cats that are prone to it, these oxalates can contribute to calcium oxalate crystals and stones in the bladder or kidneys. In a healthy cat, an occasional small bite isn't known to cause trouble, but it's not a veggie to put on the menu.
How much?
One or two cooked, chopped, plain leaves once in a while at most, and only for cats with no history of urinary or kidney issues. No creamed spinach, spinach dip or spinach pie.
The risks
- Calcium oxalate crystals or stones in cats prone to them
- Worsening of existing kidney disease
- Stomach upset if a large amount is eaten
- Creamed spinach and dips: dairy, butter, salt, garlic
Your cat ate some: what now?
A small amount is usually fine for a healthy cat; keep an eye on it for 24 to 48 hours. If your cat has had stones or crystals before, or is being treated for kidney disease, let your vet know. In any case, call your vet if your cat strains to pee, keeps going to the litter box with little result or has blood in its urine: a blocked cat is an emergency.
Better options
If your cat likes greens, lettuce, zucchini or cat grass are much lower in oxalates. For urinary health, what matters most is plenty of water and wet food.
Common questions
Does cooking spinach reduce oxalates?
Boiling removes some of them, as long as you throw away the cooking water, but plenty remains. It doesn't make spinach suitable for a cat with urinary problems.
Why is there spinach in my cat's food?
Some recipes include small amounts of spinach. In a complete, formulated food, levels are controlled, but if your cat has a history of oxalate stones, ask your vet which diet is best.
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.