How does the frog effect the Blood flow ???
Something I have never understood .

biomechanics
chris

chris bunting wrote:
That helps.

The very nature of the composition of the frog/plantar cushion enables it to act , through the application and release of pressure/force on it, to aid in circulation. Further, because of its action on the lateral cartileges and their subsequent action on the venous plexus' of the hoof, circulation is created and maintained.

Analogously the frogs are akin to pumps in that they provide a mechanism to move venous blood out of the hoof.

Rick

In post #27 of this thread http://www.horseshoes.com/forums/showthread.php?t=11654&page=2 I explained a possibility. You are supposed to read posts Ray.


Ronald Aalders

The process of weight bearing is responsible for pumping blood from the foot back towards the heart and this may play a dual role, the vascular pressure acting as an hydraulic cushion to absorb concussion as the foot takes weight.

It's suggested that as the foot is brought to the ground, veins within the foot come under pressure. The pressure forces blood along the vessels and through the digital veins up the limbs. At the same time the resistance of blood being forced through may help to absorb pressure as the foot is placed on the ground

In the case of cartilege It is clear that the only way that they can be feed ,so to say is throught compression/ movement and if I remember that the only way..
But Its not clear to me that anything else effects the blood flow apart from the heart ..and the heart pressure/ circulation .

Blood flow is Blood flow and if the pressure was in the game then the hoof/lower leg would have to be able to stop the blood flowing back up the arteria some how ,or that pressure would just push the blood away from the area that is compressed......OR????

Rick Burten wrote:
Can you give us more info on what type of action lateral cartilages experience?

Ray_Knightley wrote:Not sure where I heard this, at some clinic I guess. But its my understanding that the blood vessels in the leg has one why flapper type valves that stops the blood from flowing backwards as it being forced backup the leg. I think I said that right.

Ray_Knightley wrote:With the exception of cardiac circulation, arteries carry blood away from the heart and veins carry blood to the heart. Blood pressure keeps the blood in the arteries from 'back flowing' and one way valves in the veins keep the de-oxygenated blood from doing the same.One way valves in the veins of the legs serve that purpose, while the blood pressure in the arteries does the same.Which succinctly describes how the venous plexus of the hoof operate.

Rick

lonestar wrote:Sure.

The plantar cushion compresses the veins of the venous plexuses against the LC's and the LC's cause compression of the veins against the inner surface of the hoof wall.

As weight on the hoof increases,the thin walled venous vessels of the sensitive structures are compressed between the hard hoof wall and p3. When the veins of the venous plexus on either side of the lateral cartilages are open, blood is pumped in to the venous plexuses by that action. As the veins of the venous plexuses on either side of the lateral cartilages are first constricted and then closed by the increasing downward weight and concurrent pressure, the blood contained in them is pumped up the leg. At that point, any blood remaining in the venous vessels of the sensitive structures is locked in the foot and forms a hydraulic cushion between p3 and the wall.

Rick

Some of Chris Pollit's early work with a cadaver leg and a load press involved pumping fluids through the blood vessels as he loaded and unloaded the leg. Loading the leg prevented fluid flow through the hoof. In the presentation that I heard, he did not postulate the mechanism that caused this, but if this shut-off mechanism is both in the veins leaving the foot and the arteries supplying the foot it would trap the blood as the leg was loaded to perhaps give the hydraulic shock absorber effect. It would also explain why a severely lame horse will often founder on the opposing good leg. There will be compromised blood flow in the heavily loaded good leg and if he doesn't move around to periodically unload that leg, founder seems likely.

I'm sure there has been other more recent work done, but I'm just not aware of it.

Ray_Knightley wrote:
Ray,

Not that I seriously think that I could teach you anything but,... I was told once to think of it like a toilet plunger. When it's compressed it pushes the blood up the leg and when pressure is released it pulls blood down the leg. I also have heard about the one way valves in their blood vessels that Gary mentioned.

David

quote p 31 "shoeing for performance" haydn price and rod fisher.
when filled the blood vessels within the foot act as a hydraulic system , assisting in absorbing concussion . no major blood vessels are present in or around the frog so that , contrary to popular opinion , the frog does not have a direct pumping action in blood circulation.
chris

there are no valves in the equine leg below the knee.
chris