Your dog needs a bath and you don't have any dog shampoo on hand. Let's concede that human shampoo 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.
For knowing more on this we need to understand the difference between human skin and dog skin. A highly important component of skin is what is called the acid mantle. This is a lightly acidic layer that covers the skin, serving as a barrier to protect the porous topmost layer of the skin. The stratum corneum is responsible for keeping the outer body well hydrated.When we bathe, using soaps and shampoos, we wash away this layer of acidic oil. This is why most human shampoos and soaps are formulated with moisturizers to replace the protective layer that has been scrubbed away. If the stratum corneum is left unprotected; it is open to a host of microorganisms and may invite skin irritations.
The normal range of skin pH levels for humans is 5.2 to 6.2, which means it tends to be on the acidic side, and shampoos and skin products are formulated specifically to maintain this balance.
Now consider the relative pH balance for dogs. Depending on breed, gender, climate, and the anatomical size on the dog, the pH levels range from 5.5 to 7.5, tending toward a more alkaline concentration. Therefore, if a shampoo that is formulated for human skin is used on a dog, the dog's acid mantle will be disrupted, creating an environment where bacteria, parasites and viruses can run rampant. Unknowingly, many pet parents will repeat washings of their dogs because of the smell caused by a proliferation of bacteria, making the problem worse as the skin's acid mantle/pH level becomes more imbalanced.
Like you would look for a shampoo that helps maintain the pH balance of your own scalp, you should also concentrate on finding a shampoo with a pH balance that is specifically balanced for a dog's skin. Do read the labels, making sure that there are no artificial fragrances or colors added to the shampoo. Look for natural ingredients and fragrances to look for should be natural; coconut, lime, verbena, chamomile, lavender, eucalyptus and citrus are some examples of clean, pleasant fragrances, some of which also do double duty as insect repellents. If you can find 100% natural dog shampoos, even better. So go for the good stuff and you won't mind when your dog places his paws on your lap for a friendly hug.