We have iron in our well water and when he drools after drinking it turns some of his chest orange. We use GNC whiting shampoo. It works well. Doesnt get the stain all the way out nothing will. But for just dirt it should work really well.
I don't have much white on either of my boys, but I grew up with a Westie, and her breeder and my mom used to rinse her with a weak mixture of the old fashioned laundry bluing. It really took any yellow out of her coat and made her very white. Not sure if it's available anymore.
I used Mrs Stewart's on Hugo for years. Works pretty well. Takes a while to get really yellow stains out. Fair warning, though...
Be sure to mix the bluing in with your shampoo and don't let it set on the white parts of your dog's coat too long without lathering it up. Don't just squirt it directly on the dog unless you want a tattooed effect. A little goes a long way so just a moderate squirt in the shampoo should work.
It's best to shampoo a small area at a time and then lather. You don't have to rinse it out right away, just lather it up some and squeeze it in before moving to the next area. Otherwise you will have a black and blue dog (think little old ladies with blue hair). The blue does wear off pretty quickly though, should you dye some of his fur accidently. Doesn't hurt the black at all. In fact, I think it deepens it.
Thanks for the tips! I'll mix it and use it sparingly. And brush him when he is completely dry. By the way Puppypeoplenj, I am lusting afer your precious baby. I take it you got him/her from Bearscamp. One of hers was on the cover a recent Newf Tide and I was stunned by his beauty.