My dog is an extremely picky eater, and well - vegan. Dogs are omnivors and therefore can be vegan (Cats - not so much). They do need some special nutrition and I therefore choose a well balanced vegan kibble, and treat her with a vegan canned food from time to time. Dogs also love seitan, and I use a homemade variety for training treats.
Several vegan dogs have lived longer than average dog lives, for example, Floyd who lived to 20 and Bramble who lived to 25 (see more in the book: Bramble; The dog who wanted to live forever).
I started eating a whole food plant diet for my health about 7 years ago and over time became grossed out by my dog's food. I did research and found that my dog could switch to veggies too. My vet has said that she is one of his healthiest patients. In fact, he stated that about 80 percent of his animal patients are overweight or obese and with the illnesses that connect to being overweight. My dog is lean, active and extremely bright - often muddy. 
You might want to reconsider a vegan diet for your dog - make sure to select a balance diet.
Such a beautiful and healthy looking dog!