Eh, not really. It absorbs into the hair to strengthen from inside out, whereas silicone-based detanglers coat the hair strands so they slip apart. So it's not really going to help knots unkink, but moisturized hair is less likely to knot up in the first place; after using it regularly, I find I have less knots to detangle.Cynical does it work as a nice entangler too?
I found with the mane and tail, it works best if you shampoo using their shampoo , then condition.There's something called Mane and Tail that is a very good conditioner for your horse. As already suggested, I'd be sure your horse has a healthy diet and teeth are sound.
Also, you might try a supplement, if necessary. The mane and tail should be soft and shiny.