List of Foods Bad for Cats

Veterinarians tell plenty of horror stories of companion pets eating chocolate during holidays such as Easter, Christmas and Halloween. While dogs are more likely to munch on chocolate due to their love of sweets, cats also eat the human treat in error. It often leads to death. This is because chocolate is made by roasting the seeds of the theobroma cacao plant. One of the byproducts is theobromine, a bitter alkaloid that metabolizes at an incredibly slow rate in a cat's digestive system where it reaches poisonous saturation levels, according to the Vet Info website. Humans have more active digestive systems, thus allowing them to avoid the poisonous effects of theobromine.

Chocolate also contains caffeine. One of caffeine's downfalls for kitty is the reason why humans consume it: It is a methylxanthine. For humans drinking it in moderation via coffee or hot chocolate, it simply serves as a wake-up call. But for the smaller central nervous system of a feline, it causes hyperactivity, excessive thirst, abnormal heart rhythm, tremors, seizure and even death, according to the ASPCA.

The slower digestive system of a cat is also an inefficient place for alcohol. While it might seem like a little taste of whiskey might calm down an excited cat, chances are likely that kitty will end up with more than just a feline hangover. A cat's liver is quickly overwhelmed by alcohol, causing significant cellular damage. As with humans, alcohol causes vomiting in cats, and too much of it can put a cat's smaller bodies into toxic shock.

Cats should not eat onion, garlic or leeks. This applies even if the vegetables are softened through cooking. Root vegetables contain a substance known as N-propyl disulphide, which doesn't negatively affect humans. In fact, it is what causes these root vegetables to taste sweet after it evaporates through cooking. However, when ingested by cats, it attacks their red blood cells, often leading to anemia, according to the Messy Beast website. Potatoes and tomatoes -- particularly green tomatoes -- are also off-limits for cats. They contain solanine, which in even trace amounts causes drooling, confusion, diarrhea, vomiting and weakness.

According to the ASPCA, veterinary researchers have not yet identified the toxic culprit in grapes as far as the health of cats are concerned. They do know that grapes cause kidney failure. Since a raisin is a dried up grape, the same ban applies to it.

Just the thought of dog food might be offense to a finicky feline, yet you might not hesitate to give kitty some of the dog's food. From a purely nutritional standpoint, it's a flawed idea. According to the Pet MD website, dog food is missing some key elements that cats need. The first is vitamin A. Dogs can metabolize betacarotene into vitamin A; cats cannot. A dog's body produces its own taurine, which is an amino acid that aids in the prevention of cardiac disorders. A cat's body does not. Cats also require much higher levels of protein in their diets than do their canine counterparts.