I found something very honest, so had to repost…
When asked “Newbie here-can i wash my dog with my shampoo or soap ?”
Shineillusion, Senior Member (Joined: 24 Jan 2005, Posts: 676, location: Illinois, USA) posted on Wed Apr 18, 2007 at 1:33 am:
“I’m a dog groomer with over 30 years experience. I also worked for a large pharmaceutical company for 2 years, with the chemists and veterinary dermatologists who develop, among other things, dog shampoos.
So it will probably come as a surprise when I say YES, you can use human shampoo on dogs. But do dilute it first. About a tablespoon of shampoo to a gallon of warm water should do the trick. Apply it to dry coat, let it soak about 5 minutes, then rinse, rinse, rinse. When you think you have it all rinsed out, rinse again.
There’s nothing magical about dog shampoo. They draw from the same chemicals to make dog shampoo as they do to make human shampoo. And contrary to what people (and dog shampoo manufacturers) will tell you, there’s little difference.
That pH thing? Not all that important. Shampoo is mixed with a great deal of water. The pH of water varies by area. No one ever suggest testing the pH of your water, now do they? Why do you suppose that is? Because it’s not that important. A spoonful of shampoo in a gallon of water isn’t going to change the pH of the water to any great significance.
The whole “Dog skin has a different pH than human skin, so you have to use dog shampoo” is simply a marketing ploy meant to separate you from your hard earned cash. True, dog skin tends to have a higher pH than human skin. But the pH of dog skin also varies by breed. German Shepherds have the highest, Labs the lowest. But dog shampoos are not marketed with the disclaimer “DO NOT USE ON GERMAN SHEPHERDS” or “DO NOT USE ON LABRADOR RETRIEVERS” simply because the pH of shampoo is not all that important.
And having worked with the folks who manufacture this stuff, you might say I have this straight from the horse’s mouth.”