Warnings from the vets that you should not give chocolate to dogs is fairly common.

People are also cautioned against giving aspirin to them, although a few vets have recently "prescribed" aspirin for very special conditions. It probably would be best to discuss each case with your own care provider if you consider aspirin for any doggy use.

A number of vets have insisted you should "never give popcorn to a dog." The warning likely is because when they sniff while considering whether to eat it, popcorn is light enough to be sucked into their nose and can cause irritation and infection, although I've never known a vet who gave a reason for the warning.

The traditional lore that "wild dogs ate meat so all dogs must have meat" is largely mythical. It has been amply demonstrated that whether or not the earliest dogs were mainly or exclusively carnivores, studies of their evolution have shown that they've been associated with their human omnivore companions long enough (16 million years?) to be fully as omnivorouse as we are and can be healthy eating very much the same diet we do. A regular evolution toward handling increasingly humanlike diets is documented over many millenia.

There are a few dietary exceptions that make some human foods less beneficial to dogs, and a very few nutrients that are more beneficial to dogs than to us; but for the most part a balanced doggy meal can be about anything you can make it from - that's mostly the same stuff you yourself would eat. (Slightly more caution might be advisable relative to the claim that "if your dog eats it you can too," although that's not necessarily based on nutritianal analyses alone.)

Table scraps straight off the table can be hazardous, if they contain small bones or ones that might splinter (like fowl or rabbit ribs?) but of course our dogs deserve more attention to having a healthy diet than we worry about for our own consumption. Almost any commercial food, wet or dry, will provide all the nutrients your dog needs, and may be a "better balanced" diet than what you eat, so using that instead of making a garbage can out of your pet may be the better choice.

Dogs are also about as variable as we are in how efficiently they use the foods that go into them, so there are cases where "special diets" can help them if they suffer from poor utilization of some specific nutrients. Such cases probably are a lot less common than the advertisers claim.

(I once thought, for two years, that my asparagus had mysteriously died out, before I found that my poodle was gnawing it off at the roots as fast as it sprouted because he really loved that stuff. But he wouldn't touch the stuff out of a can.)

John