Some foods which are edible for humans, and even other species of animals, can pose hazards for pets because of their metabolism. Some may cause only mild digestive upsets, whereas, others can cause severe illness, and even death.

The following common food items should not be fed (intentionally or unintentionally) to your pet. This list is meant to serve as a guideline to prevent possible poisoning. If you feel your pet is having symptoms of toxicity from food or other substances that have possibly been ingested you should call your veterinarian and poison control immediately.

Alcoholic beverages
Can cause intoxication, coma, and death.

Avocado
Avocado leaves, fruit, seeds and bark contain a toxic principle known as Persin. A common variety grown in Guatemala, appears to be the most problematic. Other types can have different degrees of toxic potential. The safety of other foods containing avocado is not easy to assess so foods containing avocado should be avoided.

Meat Bones and Fruit Pits
Can cause obstruction or laceration of the digestive system.

Chocolate (all forms)
Dogs tend to be most commonly affected but chocolate can also be toxic to cats and other pets. Depending on the type and amount ingested, chocolate can cause vomiting, diarrhea, hyperactivity, panting, abnormal heart rhythm, tremors, seizures—and even death in severe cases. As little as 20 ounces of milk chocolate—or only two ounces of baking chocolate—can cause serious problems in a 10-pound dog

Coffee (all forms)
Caffeine and other stimulants when ingested in significant amounts can potentially produce clinical effects in dogs ranging from vomiting and diarrhea to panting, excessive thirst and urination, hyperactivity, abnormal heart rhythm, tremors, seizures and even death in severe cases.

Eggs ( Raw )
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.

Fatty foods
It is important to keep in mind that any food not part of your pet's normal diet, especially if it’s high in fat or salt can cause gastrointestinal upset. The consumption of large amounts of fatty or spicy foods may also lead to pancreatitis, a serious inflammatory condition of the pancreas. High fat content foods should always be given to pets only in small quantities.

Garlic
Garlic does have toxic potential to pets, and is generally more potent than onion, also a member of the Allium species it can cause changes in red blood cells in dogs and cats. Even at low levels of exposure to garlic, some change in red blood cells is likely. Generally, it takes either a fairly large single ingestion or chronic exposure. These effects are also somewhat more likely to be seen in cats, as their red blood cells have shorter life spans and they're more likely to have bone marrow issues. Some dogs may also be genetically more susceptible to problems from garlic ingestions .An occasional low dose, such as those found in most commercial pet foods or treats, would not likely cause problems. It is best to avoid exposure to larger quantities and avoid any concentrated forms.

Macadamia Nuts
Contain an unknown toxin, which can affect the digestive and nervous systems and muscle. Lethargy, vomiting, and hyperthermia are initial symptoms with progression to ataxia or hind-limb paresis. Also seen are tremors, abdominal pain, lameness, joint stiffness, and pale mucous membranes.

Milk and Dairy Products
Some adult dogs and cats do not have sufficient amounts of the enzyme lactase, which breaks down the lactose in milk. This can result in diarrhea. Lactose-free milk products are available for pets.

Moldy, Spoiled Foods or Garbage
Ingestion of these types of substances by dogs is not uncommon. Cats tend to be more selective about what they eat. Food poisoning can be caused by bacteria including Escherichia coli, Staphylococcus, Streptococcus, Salmonella spp., Bacillus spp., Clostridium perfringens, and Clostridium botulinum, or Penitrem-A (a neurotoxin). Each bacterium affects the body in a different way, but all can produce potentially life-threatening diseases affecting multiple body organs.

Onions, Onion Powder
A member of the Allium species it can cause changes in red blood cells in dogs and cats. Even at low levels of exposure to onion, some change in red blood cells is likely. Exposure to onion and onion powder should always be avoided.

Raisins and Grapes
Both grapes and raisins appear to cause renal failure in dogs when large amounts are ingested. The exact toxic component or the mechanism that causes renal failure is not known. It is also not clear if long-term ingestions can lead to the same effects that a large one-time ingestion can., it is advisable not to give grapes or raisins to dogs in any amount.

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

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

Xylitol
Some breath-freshening products and gums contain the sweetener xylitol, which has the potential to cause a sharp drop in a dog's blood sugar. This can result in depression, loss of coordination and seizures, and in some cases, liver damage