you can also use the neem for dogs to generally improve the skin health and the coat of your dog, then using neem oil extract is probably fine. if you are hoping to fix some problem, like fleas, ticks, mange or similar, then you have much better chances with raw, unrefined neem oil.
Neem oil is no different from other natural substances. the moment you start processing and refining them, they lose a lot of their active ingredients.
making Neem dog shampoo :
just mix neem oil into your normal dog shampoo at a rate of 1 to 5 ml for every 100 ml of shampoo. use less if your dog does not have any problems, and more if it does.