Dogs love to eat, and they're usually happy to tear into anything offered them, especially if it smells and tastes good. Unfortunately, human and canine digestion and physiology are not alike, and some foods we can process without any problem are potentially very dangerous to dogs. Even cat food, which is too fatty and has excess protein, is not recommended.
Giving the dog items that would otherwise be destined for the trash is often a bad idea. While we abuse our own systems by consuming massive amounts of salt and sugar, a dog's system is unequipped to handle them. Cooked fat or beef can cause cancer in dogs, and the fat can also trigger pancreatitis. Beef stew, Chinese food, baby food or pizza might contain onions, onion powder or garlic, which contain thiosulphate. That is especially damaging to dogs' red blood cells. The result can be vomiting, diarrhea, breathing problems or liver damage. If mushrooms were also added to the stew, your dog could go into shock or even die from ingesting them. Ingesting cooked liver can adversely affect the dog's bones and muscles by creating vitamin A toxicity.
Most people know enough not to give fish or chicken bones to pets because of the choking danger they present, but this caution rarely extends to other types of bones. Dogs love to gnaw on bones, and they are often given cooked bones from meat dishes. But these, too, can block or even lacerate part of the digestive system.
Sweets and Other "Treats"
While the dog might appear to enjoy sweets, they are generally very bad for the canine constitution and should be kept out of the dog's reach. Chocolate is a major substance to avoid because it has cardiac stimulant and diuretic properties that are bad for dogs. The most serious effects of a dog consuming chocolate can be coma and death. Cooking chocolate and cooking powder, which have the most serious concentrations of the harmful ingredient theobromine, are to be kept away from dogs in all cases. Dark or semi-sweet chocolate are also especially hazardous. Nuts, particularly macadamia nuts, must never be given to dogs as they can have terrible effects on them. Other exotic canine "treats" to avoid include grapes, raisins, citrus and especially alcohol, which can kill dogs. Uncooked bread dough should never be shared with a dog. As it expands in the belly, it might stick in the digestive tract. Milk can be bad if the dog is low on lactase enzymes.