Raw egg whites contain an enzyme called avidin, which decreases the absorption of biotin (a B vitamin). This can lead to skin and hair coat problems. Raw eggs may also contain Salmonella.

Gum contains xylitol, an artifical sweetener that's also commonly used in human food. Xylitol is known to cause a rapid decrease of the blood sugar content and thereby potentially cause death.

Raw fish contains thiaminases, which break down Thiamin (Vitamin B1). Loss of appetite, seizures, and in severe cases, death are known problems associated with raw fish consumption in cats.

Avocadoes contain persin, an oily toxin that causes both cats and dogs to vomit and have diarrhea. All parts of the avocado are toxic to animals as the persin originates in the pit but its oil spreads to the fruit and skin of the food.

Onions contain a substance (N-propyl disulphide) which destroys red blood cells in the cat, causing a form of anemia called Heinz body anemia. Garlic contains a similar substance in a lesser amount. Tomatoes and raw potatoes contain a poisonous alkaloid called Glycoalkaloid Solanine, which can cause violent lower gastrointestinal symptoms in your pet.

It's becoming more widely known that chocolate is very toxic to both cats and dogs. Theobromine is the offending substance here. Caffeine and other stimulants, including theobromine (found in chocolate), can poison cats. Do not feed your cat these "people foods" or leave them out where the cat could reach them. It is wise to just feed cats a commercially prepared cat food and never feed them food meant for humans, especially "sweets."

These foods' toxicity has only recently been discovered, and although the only studies have been with dogs, it is also believed that these fruits may also affect cats adversely. In dogs, the mass consumption of grapes has been known to cause acute kidney failure and eventually death.

Although milk is not toxic to cats, it may have adverse effects. Simply put, adult cats fed a nutritious diet don't need milk, and many cats are lactose-intolerant, which means that the lactose in milk and milk products produces stomach upset, cramps, and flatulence. If your cat loves milk, and begs for it, a small amount of cream may be okay, two or three times a week. Cream has more fat than regular milk, meaning it will have a lower lactose content as well.

Accidental ingestion of dog food will not cause aproblem. However, regular feeding of dog food to your cat isntead of their regular cat food may result in malnutrition and heart conditions.

These bones can cause obstruction or laceration of the digestive system.

As mentioned before there are many plants that are harmful to cats. Plants such as Poinsettias (large red, white, pink, or mottled leaves contain milky irritant sap). can cause problems such as vomiting, anorexia and depression. Although the symptoms are generally self-limiting and treatment is rare, it is important to keep your pet away from this plant. In the event that your cat does digest part of a Poinsettia you should take your cat to the vet. Your vet may recommend limiting food and water intake for 1 or 2 hours. Another plant that is harmful to your cat is Lilies, in particular Easter Lilies, Tiger Lilies, Japanese Show Lilies, Rubrum Lilies, Lily Hybrids, and Day Lilies. These plants have been known to cause kidney failure in pets and should be kept in an area where your pet can not reach them. For a partial list of other plants that are harmful to your cat please see below.