- The IM doesn't tear apart. It holds together quite well, as they usually are not in heavy work.

-Nails destroy the sensor

-I have not examined a heart bar shoe. There are other reports that increased pressure on the heart bar reduced pressure on the hoofwall, although not to the effect I measured with this effect. Interestingly, what do you think would happen to the frog pressure with a heart bar as the hoof grows? How about the pressure with this technique?

I have not measured clogs and IM, although when I have measured a hospital plate and IM underneath the load is primarily on the hoof wall

reillyshoe wrote:
I am going to proffer a guess that with an upright, high heeled foot, the frog plate decreases the applied pressure as the wall at the heels growth rate exceeds that of the frog...and OTOH, a low or underrun heeled foot, the frog plate increases the applied pressure as the frog's proliferation exceeds that of the hoof wall's vertical depth...and a range of increase/decrease in pressures depending on the conformations of the foot that fall between the upright and the low/underrun.

reillyshoe wrote:
Seeing how easly words can be taken out of context and threads are normaly not entirely followed. One day we will read somewhere on the INTERNET where Patrick Rielly was quoted by Barefoot trimmers that "Nails destroy the Sensor".

I can honestly say I have really enjoyed the back and forth on this thread,very interesting seeing the way differant professionals see the same thing and actually converse about it;)

centexferrier wrote:
I agree, very interesting exchange of ideas and information. I hope Cecil sticks around, he reminds me of my shoeing instructor. He also treated Laminitis with heart bars at Tufts with a high success rate.

You put Cecil's and Jaye's information together and it makes sense how frog support can relax the pull of the DDFT. I would also add something Dr. Myers shared awhile back on the cause of sidebone. He felt it was due to laminitis. If you consider the lamina is inflamed and painful around the entire hoof capsule it would make sense the addition of frog support would be a good way to relieve pain and relax the DDF muscles. Pain is not only in the toe region of a laminitic horse.

Phil Armitage wrote:
Mr. Armitage,

Perhaps I missed this or just haven't made the connection as of yet. Let me provide my thoughts and then you and/or others can let me know where I am missing the necessary information or connections to arrive at the conclusion that adding frog support decreases 'pressure' on the ddft.

1. First we should clarify the terminology 'pressure' vs. 'tension'. It is my understanding that tendons are used for applying tension and as such are intermediaries between muscle heads and bones. Tension itself is simply the manifestation of a pulling force. The chain of events is muscular contraction, tendon tension, bone movement (or at least force in the direction of the attached tendon's tension). The term pressure is descriptive of a pushing and/or pressing force, neither of which are direct functions of the ddft. Again, this is my understanding, but adding frog pressure results in a transmission of that pressure to the overlying digital cushion. The digital cushion disperses that pressure in a multidirectional fashion, however, a modicum of that dispersal is still directed proximally, resulting in increased pressure to the overlying ddft...and to the navicular bursa, navicular bone, coffin joint, etc. So as far as a HB shoe decreasing pressure on the ddft, I don't see how that is possible...unless it is not in contact with the frog and is therefore serving as a protective application, preventing pressure from being applied to the frog.

2. He can correct me if I am wrong here, but I don't think what Jaye was saying indicates decrease in tension of the ddft. Animals tend to avoid pain. There may indeed be compensatory muscle contractions, but I don't believe these contractions lie within the same musculotendinous structure as the one experiencing and/or causing the pain response. Ex. if your calf muscle is injured, you are going to modify your stance and try to maintain motion by exerting greater contraction in other muscle groups so that the role of the calf muscle is reduced in your support and forward motion. Same basic principle in the horse. If the contraction of the ddft is causing pain, the modified static stance and the dynamic 'limp' is indicative of the horse avoiding that pain. If the horse were to increase contraction of a muscle group that was the source of the pain, or whose contraction led to pain elsewhere, this would be counter productive to the healing process and the source of further damage. As such, if my understanding of the above is correct (which it is certainly subject not to be), it would seem to me to be counter productive and counter the utility of the proprioception systems for a horse to increase contraction in the ddft during a laminitic event; whether for stabilization or for motion. If anything, I would think (and again, I may be wrong), that a decrease in the pain response would be inversely correlated with an increase in contraction of the ddft...thus making the horse more comfortable results in an increase of activity/muscular contraction...and the reason bute is often discouraged in the recovery process. Either way, from a mechanical or a neurological perspecitve, I don't see how adding frog 'support' decreases either pressure or tension in the ddft...but I welcome the discussion to the contrary as I have been wrong many, many, many, many...well, you get the picture.

I think your #2 paragraph explains why people tend to run to the "back cracker" when a horse is alittle off. When the horse has an injury or insult the muscles do just as you say and the attached tendons and ligaments suffer as a result? Treating the insult would be my first thought and let things settle down as the area heals? But I too have been wrong about alot of things also?

Equine Vet J Suppl. 2006 Aug;(36):377-82.
Effects of egg-bar shoes on the 3-dimensional kinematics of the distal forelimb in horses walking on a sand track.

Chateau H, Degueurce C, Denoix JM.

UMR INRA-ENVA de Biomécanique et Pathologie Locomotrice du Cheval, Ecole Nationale Vétérinaire d'Alfort, 7, Avenue du Géneral du Gaulle, 94704 Maisons-Alfort, France.
Abstract

REASONS FOR PERFORMING STUDY: Understanding of the biomechanical effects of egg-bar shoes remains incomplete because kinematic studies are usually performed on hard tracks and with skin markers that do not measure the actual 3-dimensional (3D) movements of the 3 digital joints. OBJECTIVE: To quantify the effects of egg-bar shoes on the 3D kinematics of the distal forelimb in horses walking on a sand track. METHODS: Four healthy horses were equipped with ultrasonic markers fixed surgically to the 4 distal segments of the left forelimb. The 3D movements of these segments were recorded while the horses were walking on a sand track. Rotations of the digital joints were calculated by use of a joint coordinate system. Data obtained with egg-bar shoes were compared to those obtained with standard shoes. Mean differences were expressed in a 0.95 confidence interval. RESULTS: With egg-bar shoes, the initial sinking of the heels into the ground during landing was reduced and the heels were raised by up to 5.1 degrees (3.5-6.7 degrees) compared to standard shoes at mid-stance. Concurrently, maximal flexion of the distal (DIPJ) and proximal (PIPJ) interphalangeal joints was increased by up to 3.2 degrees (2.2-4.2 degrees) and 1.8 degrees (1.1-2.5 degrees), respectively, at the beginning of the stance phase. At heel-off, extension of the DIPJ was reduced by 3.8 degrees (2.6-5.0 degrees). In extrasagittal planes of movement, egg-bar shoes prevented sinking of the medial quarter into the ground which led to a slight decrease of DIPJ medial rotation and lateromotion. CONCLUSIONS: Egg-bar shoes prevent the heels and, to a lesser extent, the medial side of the hoof from sinking into the ground on a sand track. They contribute to a decrease of DIPJ maximal extension at heel-off and to hoof stabilisation in the transversal plane. POTENTIAL RELEVANCE: Such quantitative results support the clinical indications of egg-bar shoes.

Gary Hill wrote:
Mr. Hill,
This would be what I refer to as a complimentary lameness ghost chase...and if the original offending pathology can be diagnosed and addressed, I too feel that the associated secondary lameness(es) resolves in due time...most of the time.

Mr. Reilly,
This is what I gather from the posted abstract: egg bars provide elevation in soft footing...which reduces the tensile force on the ddft. I assume this is the corollary you are making with the heart bar? As long as the substrate in the horse's environment is soft, and since most of the stalls are deep in shavings, the HB, or any other bar connecting one branch to another, would provide heel elevation in this environment. Correct?

scruggs1 wrote:
Precisely, Mr. Scruggs. The increase in caudal surface area from a heart bar shoe might result in a decreased strain on the DDFT when in soft footing.

scruggs1 wrote:
I stand corrected and now see how a HB can aid in elevation in soft footing. I sincerely appreciate you helping me make that connection.

reillyshoe wrote:
scruggs1 wrote:
Will you give me some hints here? Am I on the right track or has my train left the tracks?

You are not corrected; see qoutes. The study is reffered to horses walking on a track not horses afflicted with laminitis in a box stall.
If the horses were walking around and studied they must be laminitic with heartbars on. The study is not relavent, IMO, to this discussion. Extrapolation is not good.

Mr. Perry,
The study concluded that the change in hoof position occurred at impact due due the increase in surface area differences created by the shoe. A stall generally has a deformable surface, and the caudal surface area of the heart bar shoe is even greater than that of an egg bar shoe. The mechanical situations are related if not totally analogous.
I think we have all seen a laminitic horse standing in soft footing with the heels banked with any shoe/trim, but it is possible that a shoe with more caudal surface area would make this easier. This has nothing to do with frog pressure, just the characteristics of the shoe.

scruggs1 wrote:
John the way I see it frog support shares the load. With laminitis pain is in the affected lamina and sole corrium. Unloading the hoof capsule and attached inflamed lamina and relieving sole pressure helps manage the pain. This along with pain meds will help relax the muscle head and reduce the pull of the DDFT on P3. Important to mention the frog/digital cushion may be more painful if loaded, frog support too far forward can apply damaging pressure into the attachment of the DDFT, Rotation and Sinkers are two different animals. Every case is different several variables come into play most important is the cause. Some others are environment, temperament of horse, quality of hoof wall, frog and sole and what the horse owner is willing to do and spend.

Mr. Armitage,
The point you just made is commonly accepted, but has not been studied. The keratinized hoof capsule is one joined piece. Does removing loading force from the hoofwall reduce lammellar strain or not?

There have been studies confirming that heart bar shoes reduce load on the hoofwall as pressure on the frog is increased. No amount of pressure will prevent P3 decent in the hoof capsule during loading.

Interestingly, frog pressure resulted in movement of P3 in a palmar direction, which seems counter-intuitive, but that is another story...