Dogs not only need, but deserve a variety of foods.
The purpose of treats is to reward and to train dogs. Nothing more, nothing less.
There are so many treats on supermarket shelves that contain numerous additives, flavourings and nasties alike. Dogs simply do not need any of these. A simple Google search will show you that the majority of ingredients in these products are of no benefit to dogs.
While I continue to try and perfect a nutritious vegan treat for us and our best friends, my personal recommendation is tokeep it simple. If you are going to use meat treats, try and feed them fresh. This isn't always possible so try plain dehydrated meat. Keep it simple.