The Hoof & Its Function

What you are about to read below is not new. It is nobody's invention, neither is it the "latest fashion-craze in hoofcare".

It is a biological and physical fact.

However, the unfortunate reality is that this common sense knowledge somehow gets lost in a whole collection of misconsception, misinformation and "traditional" beliefs. It is so bad, in fact, that these misconsceptions, and misinformation are now seen as truth and accepted values. THAT'S BAD FOR HORSES!
So, what DO you know about your horse's hooves? I mean "really"!? I tell you what I "knew", before I had to make a life/death decision for one of my horses and started researching, discovering what I should have learned the moment I started sharing my life with horses... "way back then"....

Here is what I thought was sufficient knowledge about my horse's hooves (at random)
(And I am blushing in shame, just by writing it!)
1.   When it was time to get the farrier or vet
2.   A pulled shoe is something close to a disaster
3.   An abscess needs to be dug out
4.   Iron horse shoes protect hooves
5.   The frog is something like a "pump"
6.   Thrush means the frog starts rotting because of bacterial/fungal infection
7.   Navicular is a degenerative disease and uncurable
8.   Laminitis and founder can mean the horse needs to be put down and is         caused by a variety of reasons, one: The horse is obese....
9.   Hot shoeing is good as it seals the hoof....
10. Some horses need orthopaedic shoeing
11. Soft ground is better than hard ground, because of the concussion
12. One needs to apply boots or bandages to support the tendons. 

AND if in doubt, I get an "expert" (ergo, the farrier or the vet. The vet often consulted the farrier in matters of the hoof..........)
THE ABOVE IS AVERAGE "OWNER KNOWLEDGE"! Most know more about rugs and bits than their horses' feet. Sad, isn't it?
Here is some basic and easy digestible information, EVERY horseowner should know about their horse's hooves.
The horse has evolved over the past 60 million years from being a small five-toed forest dweller (Eohippus) to a one-toed steppe animal (Equus). This development made the animal faster and therefore more efficient to survive and escape predators within the environment it needed to adapt to (forest to planes) .

Equides are the only mammals walking on only one toe.

The evolutionary remainder of the other toes are still identifiable as splint bones. The construction of knee and hock joints (several separate bones ordered into rows) are also still evidence of  the prehistoric multi-toed version of our modern time horse.
Yes, compared to our anatomy: Horses walk on the finger (toe) nail of their middle finger (toe)!
Let's talk "bone" for a moment:
LONG PASTERN BONE  (proximal phalanx)
SHORT PASTERN BONE (middle phalanx)
(distal sesamoid)
(aka distal phalanx, terminal phalanx
or P3)
Note the shape of the Coffin / Pedal bone: It is an evolutionary "masterpiece", as it has evolved into a shape of optimum weight distribution and stability. Seen from the side, it is pyramidal, seen from above or below, it has a parabolic shape.
The coffin bone in the forelimb is more circular than the coffin bone in the hind limb.
(Form and Function: Hind - propulsion and traction, Front - loading weight).
Because there are no muscles in the lower leg, all soft tissue surrounding these bones consist of a highly efficient system of tendons, ligaments and cartilages.
Correctly balanced, the hoof (coffin bone) will be a suspended (by the laminar interface) and supported (by the sole)   "foundation platform" of the harmonious curved lower leg (bone column), therefore becoming part of a shock absorbing and loadbearing mechanism.
                                                                 (Note: The above graphic on the right is a little too steep)

The Coffin bone is the only bone without a periosteum.
There is  highly metabolic tissue instead, called the "corium" (or dermis) which acts like a "vascular sponge"
that plays an important role in the circulatory function of the hoof  and is also providing a sponge-like hydraulic
buffer ("hemodynamics") between the bony structure and the hoofcapsule.
The corium is histologically inseparable from the coffin bone.
                                                                            (see sole/bar and frog  corium below and laminar/coronary corium, right)

The corium fills with arterial blood when the foot is loaded  and is in its most relaxed state (DIASTOLIC PHASE) and expresses venous blood when contracting (unloaded) (SYSTOLIC PHASE).
It is a highly metabolic tissue. 
The constant expansion and narrowing of a healthy hoofcapsule with every step, facilitates the "expression and suction effect" of the corium and therefore assisting the heart as a circulatory pump. The venous blood is expressed from the coronary venous plexus when the hoof loads and the coronary bulge is stimulated. (Yes, the wall is meant to bear weight!)
With every step the horse makes, this circulatory "suction-pump" is circulating blood through the hoof and back to the heart. That is why movement is vital to the health of hoof, heart and the entire organism. EVERY STEP COUNTS!

Peter Speckmaier, SHP and  STRASSER  Course Instructor
In Summary,


*  Protection (Protects and insulates internal living structures from mechanical and chemical damage and extreme temperature  
  flactuations that may effect the cell metabolism)

*  Traction and sure-footedness
  Correct hoof shape will provide "grip". Every feature of the hoof has got a purpose: Concavity of sole plus elasticity of  frog and bulbs provide
  "suction cup effect" on smooth surfaces. The wall rim is a traction devise. The "arrow" shape of frog, collateral grooves and bars provide an
  "anker effect" in slippery conditions.
  Since the hoof is in direct contact with the ground, the horse can feel what it is stepping on! The living tissue has "proprioreceptors" and gives
  the horse information of its position in relation to environmental conditions (terrain). For a prey animal this is a vital function needed for survival!).

*  Shock absoption through a number of features:
>   "Destructive impact energy" is transformed to "reversible structual deformation" of the hoofcapsule: The hoofcapsule draws flat and
    widens on weightbearing and contracts when unloaded. THIS FUNCTION ACCOUNTS FOR 60-80% OF SHOCK ABSOPTION!
    It is not possible when the hoof is braced by a metal rim = a horse shoe, or when the sole has lost its concavity (for whatever reason)
>  Individual compression of spiral horntubules
>  Elastic suspension of the coffin bone within the hoofcapsule (the laminar interface and elastic support of a vaulted sole).
>  Support of the lateral cartilage and the digital cushion which "catches" the short pastern on weightbearing like a sling.
>  Harmonious alignment of the bones of the lower leg, supported by ligaments and tendons.
   This harmonious alignment is only possible if the coffin bone is positioned ground-parallel for optimum stress distribution on all support structures.
Correct hoof balance is essential!

*  Circulatory Pump
As mentioned above, the hoofcapsule changes shape when weightbearing (draws flat and wide) which fills the corium with arterial blood). When unloaded (lifted, horse takes a step...), the hoofcapsule "contracts" back into its narrow state: It contracts and presses the venous blood into the coronary venous plexus. From there, and with the next step the horse takes, the blood is pushed up further. Step by step. In relation to the horse's size, the heart is only 0.5% of its entire body weight. Since there are no muscles in the lower leg, the function of the hoof as auxillary circulatory pump is vital to the organism's cardio-vascular (circulatory) health!

*  Protein Excretion
The corium is a metabolic organ with cells that excrete metabolic protein waste products: Horn.
The amount of metabolic activity of the corium is comparable with that of the liver, kidney and skin. If it is not able to function (because of lack of hoofmechanism or lack of movement), the other organs "of waste disposal" may be affected, resulting in liver, kidney and/or skin problems.
  this be you??
Note: The hoofcapsule expands as a UNIT, starting at the toe at 12o'clock. Without the descending of the solar vault, the walls can not expand!
Note: The corium sponge widens and expands to allow arterial fill when hoof is loading!
If you are interested to learn more, contact me to find out about seminars and professional mentorships!

I can assist you in becoming a competent owner trimmer  but also provide professional mentorship to hoofcare students  and  farriers.