My Azrael has "the" thickest cotton coat of all! She has enough of this cotton mess to cover a dozen dogs. I have tried more shampoos and conditioner's than I even care to think about (not to mention the kings ransom I've paid out in these products) and can save you time and money right now by just letting you know what you can do to help with this problem. Buy a pair of thinning shears and a slicker. Thin out the thick cotton coat, and make sure you use a conditioner after you shampoo. Doesn't matter what kind of dog shampoo OR conditioner you use either. If the shampoo makes a lot of suds, then I would thin it down with water. I use #1 Systems super rich cleaning and conditioning shampoo and Super rich Protein Conditioner. They are VERY concentrated and last a very long time. I buy by the gallon since it's a lot less expensive that way. I also add Vegetable Glycerine to the conditioner. During the dry winter months they get a hot oil treatment before their bath and I use a humidifier to keep the house at 50 to 55%. (( Helps with my skin and hair as well)). There is no real "quick" cure for a cotton coat, but it is if you do the little extra.
