Alcoholic beverages
Can cause intoxication, coma, and death.

The leaves, seeds, fruit, and bark contain persin, which can cause vomiting and diarrhea.

Bones from fish, poultry, or other meat sources
Can cause obstruction or laceration of the digestive system.

Cat food
Generally too high in protein and fats.

Chocolate, coffee, tea, and other caffeine
Contain caffeine, theobromine, or theophylline, which can cause vomiting and diarrhea and be toxic to the heart and nervous systems.

Citrus oil extracts
Can cause vomiting.

Fat trimmings
Can cause pancreatitis.

Fish (raw, canned or cooked)
If fed exclusively or in high amounts can result in a thiamine (a B vitamin) deficiency leading to loss of appetite, seizures, and in severe cases, death.

Grapes, raisins and currants
Contain an unknown toxin, which can damage the kidneys. There have been no problems associated with grape seed extract.

Unknown compound causes panting, increased heart rate, elevated temperature, seizures, and death.

Human vitamin supplements containing iron
Can damage the lining of the digestive system and be toxic to the other organs including the liver and kidneys.

Macadamia nuts
Contain an unknown toxin, which can affect the digestive and nervous systems and muscle.

Can depress the nervous system, cause vomiting, and changes in the heart rate.

Milk and other dairy products
Some adult dogs and cats may develop diarrhea if given large amounts of dairy products.

Moldy or spoiled food, garbage
Can contain multiple toxins causing vomiting and diarrhea and can also affect other organs.

Can contain toxins, which may affect multiple systems in the body, cause shock, and result in death.

Onions and garlic (raw, cooked, or powder)
Contain sulfoxides and disulfides, which can damage red blood cells and cause anaemia Cats are more susceptible than dogs. Garlic is less toxic than onions.

Seeds can cause intestinal obstruction and enteritis.

Pits from peaches and plums
Can cause obstruction of the digestive tract.

Raw eggs
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.

Raw meat
May contain bacteria such as Salmonella and E. coli, which can cause vomiting and diarrhea. (If you are considering a raw diet for your companion, you should educate yourself thoroughly regarding the safe handling and preparation of raw ingredients, and the proper balance of nutrients required to maintain your companion’s health.)

Rhubarb leaves
Contain oxalates, which can affect the digestive, nervous, and urinary systems.

If eaten in large quantities it may lead to electrolyte imbalances. 

Can become trapped in the digestive system; called a “string foreign body.”

Sugary foods
Can lead to obesity, dental problems, and possibly diabetes mellitus.

Table scraps (in large amounts)
Table scraps are not nutritionally balanced. They should never be more than 10% of the diet. Fat should be trimmed from meat; bones should not be fed.

Contains nicotine, which affects the digestive and nervous systems. Can result in rapid heart beat, collapse, coma, and death.

Yeast dough
Can expand and produce gas in the digestive system, causing pain and possible rupture of the stomach or intestines.

Xylitol (artificial sweetener)
Can cause very low blood sugar (hypoglycemia), which can result in vomiting, weakness and collapse. In high doses can cause liver failure.