Onions, as well as garlic and chives, can do more than cause a cat gastrointestinal irritation. They can damage red blood cells, which carry oxygen to all the body’s tissues. Keep them out of your cat’s diet, even as a minor ingredient. (For instance, don’t let your cat lick your plate of spaghetti sauce, which is generally seasoned with both onion and garlic.)
Other foods that should be kept from your cat’s repertoire: highly salty snack foods, including potato chips. Some cats will eat anything and train their owners to share, but the ASPCA points out that large amounts of salt can lead to sodium ion poisoning in pets (symptoms may include vomiting, diarrhea, tremors, and worse). It suggests people simply not let their feline family members get started on salt-heavy treats.
Finally, as much as your cat might enjoy milk, don’t give him any. Cats lack the enzyme lactase, which helps digest the lactose in milk. Thus, milk can leave a cat with gastrointestinal upset.
I have a question. If the reason cats shouldn’t have milk is because of the lactose, could a cat have lactose free milk sometimes? Thank you