Today we went at the vet and she said not to use brushes, more like comb things, because a brush just tears the fur. And after you finish untangling, "puff" it up by combing it the opposite direction.
I haven't used this technique yet since mine is just a pup.Hope this helps.
IMO vets are not groomers, and give alot of bad information on stuff they know little about. a brush is not going to destroy your dogs coat, so aslong as you use the correct brushs and combs. a slicker brush and grey hound comb will be the best products to use on this type of coat.