I always found dog shampoo to be an exaggerated phenomenon. A typical case of money-grabbing by overprotective owners. I used to wash my pony with Zwitsal and that was to my full satisfaction, as far as I could tell.

Until I sat across from a veterinarian during a dinner who told me that it is really bad to wash your dog with regular soap. Its protective layer gets damaged and cannot be restored.

The best excuse to indulge in that too decadent but oh so nice and handsome dog soap from Aesop.