The frog is the blood pump for the hoof. .... The frog compression provides both cooling and nutrients to the rest of the hoof. Very important.
I believe this '5 hearts' theory is widely accepted as outdated these days, since Dr Bob's work has shown that it is 'phooeyness'. As, far from being a 'pump', there isn't a heap of blood going through the fibrocartilaginous DCs, and blood *in a well functioning* caudal foot is slowed down
substantially, by going thru 'bazillions' of minute vessels in the LCs, which acts as a haemodynamic shock absorber.
And the blood flows through the rest of the foot before going thru these 'swizzle stick' vessels & out of the foot. There is a LOT more blood flow through the feet than is needed for nutrients to cells too.
**NB if anyone's ever heard him speak, you'll know where I get the... novel terminology!
I suggest people familiarise themselves with Dr Bowker's work(which is often quite 'heavy' but well worth the effort!), which will give you a better understanding. Here's one link to one article on his 'haemodynamic flow thoery'... http://www.barefoottrimming.com/file...mics_small.pdf
There are also 'shunts' in the vessels above the hoof which can bypass, so greatly restrict blood flow though the hoof(such as when there's too much pressure on coronal & circumflex arteries from peripheral loading), and when this happens, there is a stronger
blood flow back up the leg - that wouldn't happen if the frog/DC was a necessary blood pump either.
I think if the live sole was carefully exposed at the seat of the corn, the heels could be taken down a bit.
As said previously, I think the heels *might* be able to come down a tad more, and most likely they can be brought *back* further, without lowering them much, but I think it's very important that the horse is *comfortable* on his heels, and taking them down to 'ideal' parameters, regardless whether you feel like exfoliating to live sole, to see where it 'should' be, *may* be the wrong thing to do.