1. Grapes and Raisins - This one might not be as widely known, and that might be a result of the reason behind it being somewhat unknown as well, but grapes and raisins can cause kidney failure in dogs. It is best to avoid giving either of these to your dog at all.
2. Chocolate (& Caffeine) - Now even if you have never had a dog of your own you probably know that chocolate is toxic to dogs. What you might not know is that this also extends to coffee and caffeine. All of these items come from cacao seeds, which contain methylxanthines. This has been known to cause numerous ill effects in dogs and even death. They should be kept far away from your pets.
3. Salt - When ingested in large amounts, salt can cause pets to have excessive thirst and urination. This can lead to severe dehydration and even sodium ion poisoning, so it's best to limit the salty snacks you give your dogs. Some common salty snacks to watch out for can include pretzels, chips, popcorn etc.
4. Bread - This common table food can cause bloating and twisting in your dogs stomach. This extends to all forms of bread, from sliced to baked. Also, when eating raw dough, the ethanol produced from the yeast can cause your dog to become drunk. Obviously, you do not want that so you are going to want to keep all forms of bread away from your pups.
5. Candy. Chocolate candy should never be given to your dog. Chocolate may cintain a toxic sweenter called Xyltol which will make your dog hop skip and race to the vet.
6. Coffee. Don't give it to them, period. They Will die!