Caffiene (Coffee, pop, tea, etc)

Hops

Large amounts of liver

Yeast Dough

Sugary Foods

Salt

Peach and Plum Pit

Onions and Garlic

Mushrooms

Dairy Products

Macadamia Nuts 

Green Tomatoes

Chocolate

Raw Fish

Tobacco

Grapes and Raisins

Can affect the heart and nervous system.

Causes panting, increased heart rate, seizures, fever, and death.

Can cause Vitamin A toxicity affecting the bones and muscles.

Expands and produces gas in the digestive system resulting in severe pain, and in some cases, rupture of the stomach or intestines.

Leads to obesity, dental problems, and diabetes.

Large quantities of salt can lead to electrolyte imbalances.

Can cause digestive tract obstructions requiring surgery.

Contain sulfoxides and disulfides that damage red blood cells resulting in anemia. Cats are more prone to problems then dogs.

Can cause stomach upset and even organ damage, depending on the species of mushroom.

Most Cats, including kittens, are not capable of breaking down the lactose in milk, making them "lactose intolerant" resulting in diarrhea and abdominal pain.

An unknown toxin affects the nervous and digestive systems as well as muscles.

Contain the poisonous alkaloid Glycoalkaloid (also found in Deadly Nightshade) that results in severe and painful gastrointestinal upset.

Contains Theobromine which is extremely toxic to cats, dogs, and many other animals.

Regular consumption of raw fish can result in thiamine deficiency resulting in loss of appetite, seizures, and in the most severe cases, death.

Nicotene affects the digestive and nervous systems and can result in rapid heart beat, followed by collapse, coma, and death. Cigarette smoke effects the lungs of animals just as it does humans, but much more quickly and more severely due to their size.

Deaths in parrots have been contributed to an unknown toxin in grapes, and can damage the kidneys of dogs and cats as well.