Are these foods poisonous to dogs?

In this video you will see two dogs eating (and it would seem clearly enjoying) a number of foods often considered poisonous to dogs including grapes, tomatoes and citrus.

I have often had the suspicion that these rumours have their origins in the vivisection laboratories. There are so many cases of vivisectionists taking animals and force feeding them nothing but one ingredient until they eventually develop some kind of health problem. In Australia the healthy leafy green comfrey is banned. One of the apparent reasons for this is that animal testers force fed rats nothing but comfrey until they developed some kind of liver problem. A kind of problem that would just be put down to bad luck with a human on a SAD diet.

A good principle to stick to is that the dose defines the poison, and that the stronger tasting the food the less liberal you should be with it. Feeding your dog nothing but tomatoes would clearly be extreme and you wouldn't be overly surprised if it resulted in problems. But wet vegan tinned food for dogs and cats, Benevo Duo contains both tomatoes and avocadoes (another fruit often deemed poisonous to dogs) and yet has proved widely successful.

In my opinion people should stop worrying about a grape or two and start paying more attention to the infinite reovltingness present in standard pet food products.