If your dog is shedding brush him first, to remove as much of the loose hair as possible. I do not have a matting problem with my dogs, but those need to be removed first also.
The shampoo I use is a tearless one and very gentle to their skin. (I also wash my cats with this shampoo.) Just do not use human shampoo! It is not the proper pH for dogs. If you wish to know the brand you can e-mail me.