What Foods Are Harmful to Dogs?

A taste of chocolate might send you straight to heaven, but that same bite can be deadly for your dog. Chocolate contains theobromine and caffeine, both substances with stimulant and diuretic properties. Chocolate consumption often causes hyperactivity, restlessness, irregular heart beat, excessive panting and increased thirst and urination. Diarrhea, vomiting and tremors also frequently occur, sometimes followed by seizures and death. Even just 1 ounce of chocolate can kill a dog that weighs 10 pounds or less. Signs of chocolate poisoning might not appear for several hours after consumption, with death occurring within 24 hours.

Tasty macadamia nuts contain a toxic compound that causes temporary weakness in a dog's hindquarters along with depression, vomiting and tremors. Macadamia poisoning symptoms typically start within 12 hours of consumption and last anywhere between 12 and 48 hours. All kinds of nuts contain high phosphorus levels that can trigger the development of bladder stones in dogs.

Grapes and raisins contain a substance that triggers bouts of diarrhea and vomiting in canines. Even worse, the onset of kidney failure can occur approximately 24 hours after consuming these fruits. The seeds and pits of many fruits contain cyanogenic glycosides, a substance that can give your dog cyanide poisoning. Avoid giving your dog apple and pear seeds as well as plum, peach, cherry and apricot pits. Avocados and their pits contain a toxic substance called persin, which can damage your dog's lungs and heart. This high-fat fruit might also give your dog an upset stomach, causing vomiting and diarrhea.

If consumed in large doses, onions and garlic can irritate your dog's GI tract, damage his red blood cells and cause breathing difficulties. Although fairly rare, sprouting and green potatoes contain enough solanum alkaloids to be toxic to both dogs and their owners. Broccoli contains isothiocynate, a substance that can trigger stomach upset if eaten in large quantities, while corn cobs can cause intestinal obstruction. Tomatoes contain atropine, a chemical that often causes muscle tremors and irregular heart rhythms.

It's a good rule of thumb to avoid giving your dog raw or undercooked foods that you would never eat yourself. Raw eggs and meat sometimes contain bacteria such as E. coli or salmonella, both of which can make your dog very sick. Raw egg whites also contain the avadin protein, which can reduce your dog's ability to absorb biotin, a B vitamin crucial to canine health. Uncooked bread dough isn't good for your dog, either. The yeast can ferment and rise, causing excessive gas, abdominal pain, disorientation, bloat and vomiting.

Many dogs are lactose intolerant because they lack the enzymes to effectively digest milk sugar. Giving your dog dairy products can quickly cause him to suffer excessive gas, diarrhea and vomiting. Most dogs can tolerate small amounts of plain yogurt and cheese because they contain less lactose than other dairy products.