This is a complicated topic and I have never had any relationships with dogs. I do know though that there are many people who have 'converted' dogs to eat a vegan lifestyle successfully - and as I recall at one time the world's oldest dog (recorded) was fed a vegan diet. There are manufacturers of vegan dog food who ensure that their products meet the dog's nutritional requirements.
I have seen some people attempt to shame other people for attempting to 'go against nature' by doing this - however, I see no problem with it and the dogs appear to be fine with it from what I have seen.