I has a student in my DIY-grooming class for
Bathing beauties class, ask me why shouldn't we use our own shampoos and soaps on our dogs. This is great info on why we don't / shouldn't. This is from 2009 and suggests pet owners look for shampoos with tea tree oil. Which is still a great oil but Because the industry does not have regulation most shampoos especially those available at consumer grade do not have complete ingredient lists available. Also there is no regulation as to the quantity of tea tree oil, or other essential oils, used in shampoos for pets. I think it is still better that pet owners buy their shampoo from knowledgeable groomers or veterinarians. There is still so much to learn.
The dog needs a bath, it's after 6 p.m. on a weekday, and you don't have any dog shampoo on hand. Let's concede that shampoo made for people will clean your dog, but the question is, is it good for your dog? This may seem like a quibbling question, but it can actually have far-reaching consequences.