This may seem like a quibbling question, but it can actually have far-reaching consequences.
We'll start with the how's of people skin and the equine 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, from environmental contaminants such as bacteria and viruses. The stratum corneum is responsible for keeping the outer body well hydrated, by absorbing water and not allowing excessive evaporation to occur. 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 moisturisers to replace the protective layer that has been scrubbed away, at least until the skin is able to replenish itself after about 12 hours.
The acid mantle can also be defined as the relative pH balance of the skin. The pH scale ranges from 0 to 14, with levels less than 6.4 considered high acidity, and levels more than 6.4 considered high alkalinity. 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 human shampoos and skin products are formulated specifically to maintain this balance.
Now consider the relative pH balance for your horse. Depending on breed, gender, climate, and the anatomical size on the horse, the pH levels range from 7.2 to 7.5, tending toward a more alkaline concentration. Therefore, if a shampoo that is formulated for human skin is used on a horse, the horse's acid mantle will be disrupted, creating an environment where bacteria, parasites, and viruses can run rampant. Unknowingly, creating the the horses skin's acid mantle/pH level to become imbalanced.
Additionally, if the shampoo makes the skin feel dry, your horse will scratch at its skin, creating abrasions for bacteria to invade.
This can quickly become a vicious cycle.
We only used the highest possible quality ingredients to formulate our Horse Care and Grooming products.
All our products, that are developed to be used topically on your horse, are specifically pH balanced, to suit your horses sensitive skin.