IIRC, Milk Bones are primarily wheat. Not what I consider good for any dog...especially a Bulldog. But they taste good so most dogs gobble them up. Try to avoid grains like Wheat Corn Soy.
There are lots of really good snacks for Bulldogs available. The one we serve is Nuzzles (Duck and Cherry made by The Honest Kitchen). Keep in mind that just because a dog is large doesn't mean they have to have a large treat. All dogs appreciate a treat and even tiny treats are welcomed with enthusiasm.