Curiosity can indeed kill the cat if the feline gets into a food that can poison it. Symptoms of poisoning generally include vomiting, diarrhea, a rapid heart rate and even seizures. Because veterinarians are not always certain how much of a dose of these forbidden foods will kill a cat, your best bet is to avoid them altogether. Take your cat to the vet immediately if you suspect poisoning.
Chocolate, Candy and Gum
Chocolate, candies and gum may be sweet, but fatal to your cat. Chocolate contains theobromine and caffeine, both of which are harmful to cats. Some sugar-free candies and chewing gum, as well as some flavor enhancers, can also be fatal. The culprit in their cases is the sweetener xylitol.
Onions and Garlic
Onions and garlic in any form are dangerous. Cats must avoid contact with any part of an onion or garlic bulb no matter whether it is raw or cooked. Also watch out for the presence of onion or garlic in salts, powders and flavorings. Cats do not have the enzyme to digest onions and garlic, and consumption can result in digestive problems, liver damage and even death. Baby food -- which some people feed to their cats -- often contains onion flavoring that can be harmful.
Cats that eat out of the garbage or compost piles can also become sick or die. The fatal substance in these cases is mycotoxins, which come from fungi growing on moldy cheeses, breads and other materials. Mycotoxins are also found in English walnuts and mushrooms, both of which should not be part of your cat's diet.
A few other foods are dangerous to cats. Raw fish, which causes a thiamine deficiency, can be fatal if you regularly feed it to your cat. Even one dose of yeast dough can rupture your cat's stomach or intestines as it expands and produces gas. Grapes, raisins and macadamia nuts can also be toxic to cats.