Most of us animals instinctively know which foods will harm us, that is except for my canine cousins. They may be the muscle of the domestic animal kingdom, but when it comes to knowing what is and isn't safe to eat they aren’t the brightest  crayon in the box.
  
For us doctors one of the hardest things we have to do is to tell a devastated loving pet owner that the best friend they’ve so diligently cared for all these years is sick or dying from some people food they shared out of love. Below is a list along with the description of the seemingly innocent human foods that will either permanently harm or even kill your canine kids.

Chocolate/Caffeine:
  
Chocolate contains Theobromine, a compound that is a cardiac stimulant and a diuretic.
   
After their pet has eaten a large quantity of chocolate, many pet owners assume their pet is unaffected. However, the signs of sickness may not be seen for several hours, with death following within twenty-four hours. Symptoms include Staggering, labored breathing, vomiting, diarrhea, abdominal pain, tremors, fever, heart rate increase, arrhythmia, seizures, coma, death.
    
Cocoa powder and cooking chocolate are the most toxic forms. A 10-kilogram dog can be seriously affected if it eats a quarter of a 250gm packet of cocoa powder or half of a 250gm block of cooking chocolate. These forms of chocolate contain ten times more Theobromine than milk chocolate. Thus, a chocolate mud cake could be a real health risk for a small dog. Even licking a substantial part of the chocolate icing from a cake can make a dog unwell.
   
Semi-sweet chocolate and dark chocolate are the next most dangerous forms, with milk chocolate being the least dangerous. A dog needs to eat more than a 250gm block of milk chocolate to be affected. Obviously, the smaller the dog, the less it needs to eat.

Onions/Garlic:
    
Onions and garlic contain the toxic ingredient Thiosulphate. Onions are more of a danger.
   
Pets affected by onion toxicity will develop Haemolytic Anaemia, where the pet’s red blood cells burst while circulating in its body. Symptoms include Hemolytic Anemia, labored breathing, liver damage, vomiting, diarrhea, and discolored urine.
   
The poisoning occurs a few days after the pet has eaten the onion. All forms of onion can be a problem including dehydrated onions, raw onions, cooked onions and table scraps containing cooked onions and/or garlic. Left over pizza, Chinese dishes and commercial baby food containing onion, sometimes fed as a supplement to young pets, can cause illness.
   
While garlic also contains the toxic ingredient Thiosulphate, it seems that garlic is less toxic and large amounts would need to be eaten to cause illness.

Mushrooms:
   
Mushroom toxicity does occur in dogs and it can be fatal if certain species of mushrooms are eaten. Amanita Phalloides is the most commonly reported severely toxic species of mushroom in the US but other Amanita species are toxic. Symptoms include abdominal pain, drooling, liver damage, kidney damage, vomiting diarrhea, convulsions, coma, and death.

Grapes/Raisins:
   
As few as a handful of raisins or grapes can make a dog ill; however, of the 10 cases reported to the ASPCA Animal Poison Control Center (APCC), each dog ingested between 9 ounces and 2 pounds of grapes or raisins. Symptoms include vomiting, diarrhea, abdominal pain, and lethargy.

Macadamia Nuts:
    
Macadamia nuts are another concern, along with most other kinds of nuts. Their high phosphorus content is said to possibly lead to bladder stones. Dogs develop a tremor of the skeletal muscles, and weakness or paralysis of the hindquarters. Affected dogs are often unable to rise and are distressed, usually panting. Some affected dogs have swollen limbs and show pain when the limbs are manipulated.

Baby Food:
   
Can contain onion powder, which can be toxic to dogs. Can also result in nutritional deficiencies, if fed in large amounts.

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

Cat Food:
    
Cat food is generally too high in protein and fats for dogs. Diets too rich in protein can be a contributing factor in the formation of bladder stones.

Fat Trimmings:
    
Can cause Pancreatitis.

Milk and other 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.

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 Fish:
   
Can result in a Thiamine (a “B” vitamin) deficiency leading to loss of appetite, seizures, and in severe cases, death.

Tomatoes, Green (raw Potatoes)
   
These foods are members of the Solanaceae family of plants, which includes the Deadly Nightshade, and contain a bitter, poisonous alkaloid called Glycoalkaloid Solanine, which can cause violent lower gastrointestinal symptoms. The Feline Future web site offers a rare description of a cat which was close to death from ingesting just one cherry tomato.