Jadens coat get so dry!! Especially in the winter, I had him on Nutro as well. I changed him over to Canidaes All Life Stages and started adding grizzly salmon oil in the morning and missing link at night and I have seen an amazing difference in his coat! It is the sofest and silkiest it has ever been and is growing like crazy!!
I also use Aubrey Organics moisturing shampoo and conditioner on him when his skin seems like its getting dry again. Theri shampoos and conditioners are all organic and even some of the finest pet conditioners are not. Any shampoo or conditioner with petrolyem by-products in it...for instance mineral oil, can cause severe drying and flaking of skin. Petsilk and John Paul have mineral oils in them. I still use their shampoos and conditioners but when I notice his skin starting to get dry again I switch back over to Aubrey Organics and within a week or two it clears right back up.
You can order their products online, they also sell them at upper scale salons and health food stores. I also give Jaden a pre-oil a day before his washing, like in the morning I will oil him down with jojoba oil and let it sit all day and then that evening he'll get his bath. It's really great for the skin! I also use and run a humidifier throughout the entire winter and it REALLY helps!
Hope this helps!