The short answer: It depends.
The long answer: Spinach is a vegetable that is rich in vitamins (A, K, B6, B2, E, and C) and minerals (magnesium, folate, calcium, and potassium). Low in calories and high in fiber, it can improve a cat’s digestion, help boost eyesight, and regulate blood pressure.
Cats without any health conditions may eat spinach occasionally, but those with urinary tract infections and kidney problems should not eat it. (Even those with a history of these ailments should not consume it.) The vegetable contains calcium oxalate, which can cause harmful crystals to form in your cat’s urinary tract and aggravate her condition. If you feed your cat spinach on a regular basis, it can also increase the chances of her having a urinary tract problem.
Raw spinach contains oxalates, so it is not advisable for a cat to eat it. On the other hand, cooked spinach may be fed to your healthy cat only if it was boiled or steamed without seasonings. Onion, garlic, salt, and other flavourings are harmful for cats and may lead to poisoning.
What to do if your cat accidentally eats spinach: Observe your cat for any changes in her toilet habits. If she has a history of UTI, watch for these symptoms: difficulty in urinating; frequent urination, but only passing small amounts of urine; urinating outside the litter box; blood in the urine; crying out in pain while urinating; and increased licking of urinary opening.
In summary: Packed with vitamins and minerals, spinach is a leafy treat that may be given to a healthy adult cat. However, it is not advisable for young kittens and cats with urinary and kidney-related problems to consume this vegetable. Before including spinach in your cat’s diet, seek her veterinarian’s approval.