We've gone over some of the scientific reasons for being a vegan dog. Lets go over some of the ethical reasons.
1) Forced Cannibalism: Yes, it sounds worse then you think. Dog food processing plants can use all manner of meat in their dog food, doesn't matter if its unfit for human consumption or not. But what is shocking is some of these plants could be using euthanized dogs and cats...I know, that;s horrible. In 2004 the FDA (being concerned about the possibility that some of these plants could do something so horrible.) conducted a study on dog food, they purchased many samples and found that some of those samples contained pentobarbital. Pentobarbital is the drug that is used to euthanize dogs and cats, that means if you are using a dog food with meat in it, it could be "real dog food" as in its made from dogs!! "But it doesn't say that in the labeling?" I hear you saying very loudly, well look for "meat-by product" that work encompasses everything you don't want your dog to eat.
2) Good for the planet: As you may or may not be aware eating animals consume a great deal of resources compared to just eating the grains that we already feed them and drinking the water they are drinking. requires on the order of 4,000 lb of water to produce 1 lb of meat. That is a TON of water or to be more accurate that is 2 tons of water. This type of consumption is unsustainable and is chipping away at our finite resources, all for the sake of a burger.