LOL!
Really... shampoo is shampoo, for the most part.
Theres not very much thats different in a bottle of horse shampoo compared to human shampoo... nor to dog shampoo.
Sodium laureth sulfate... it makes bubbles which cleanse hair. Different shampoos contain different amounts of it, along with various differing moisturizing ingredients... but the idea of shampoo is the same, no matter the creature.
However... I much prefer the human shampoo by Loreal... the sulfate free line.. as my hair is much stronger and moisturized on it. I've tried quite a lot of shampoos and conditioners to find ones I like.
I dont even use Mane & Tail on my horse. For him... I use Cowboy Magic Rosewater shampoo. It's far less drying because it uses less harsh bubbling agents.
Then I use Canter mane and tail conditioner on him. Which is just as good as my human conditioner.. I'd like to try it on my hair, but it's for him
In any case... a shampoo and conditioner is never going to grow hair. Hair grows out from the roots at the top of your head, and the growth there is based on your health and nutritional building blocks available to the hair. Putting something on the outside is not going to change the growth.
But.. a really nice shampoo and conditioner.. and using conditioner regularly.. can strengthen the hair and prevent hair breakage.
I wouldn't be looking to something like Mane & Tail for mine. If I was feeling pinched and wanted a cheaper shampoo, I might get it... but probably I would get Herbal essences one instead. I don't love that one.. but it does the job and smells ok. I've used the Herbal essences on my horse... but we like his Rosewater one better.