PARTS OF THE HOOF

Illustration © PENZANCE Equine Solutions 2006. ALL RIGHTS RESERVED.

Physiology of the Parts:

1. Hoof in General:  Front hooves should be round in shape and be able to be divided into thirds with 2/3 of the ground contact  behind the widest part of the foot and 1/3 ahead of the widest part of the foot to the point of breakover. Rear hooves should be more oval shaped. Front hooves hold 60% of the horses total weight when static whereas the rears hold 40% and are meant to be able to dig in for quick take-off at which time weight shifts to rear.  
   
   The hooves should be balanced medially-laterally (side to side). That is, if drawing an imaginary line from the heel to the toe right down the middle of the hoof, the two sides should be the same. Not one side higher than the other or thinner than the other but both unilaterally the same.
   The same applies when viewing the hoof from the front. If an imaginary line is drawn straight down the middle of the pastern through the hoof, both sides should be equal and balanced.

2. Ideally, the hoof wall should be the same thickness all the way around the hoof and never left long enough to be weight-bearing by itself. In healthy, whole hooves, if one were to draw an imaginary shape continuing from the toe callous around the hoof this wide area would look like a "natural" shoe on the horse and be almost uniformly weight bearing as on a flat plane with the walls of the hooves blending smoothly and tightly into the sole. This is called the sole callous. The slight arched area in the quarters that are not flat on the ground allow for expansion of the hoof on loading.  Here is an actual photograph depicting this.
   
      This hoof has not yet been trimmed but clearly shows the thick hoofwall with no separations or dirt between the wall and the sole. The hoof sole is one solid unit. The frog, however, is showing pathological issues and is not representative of a healthy frog. The hoof is clearly in need of a major correct trim. The heels are too long so the frog does not receive any ground contact. This causes contracted heels which are evident in the above photo.

3. When looking at the horse while hooves are on the ground, the same applies for uniformity as it does when looking at the hooves from a solar view.
   
     This is a front hoof newly trimmed after removing shoes. The heels were left longer than ideal because the heels were so long before trimming that to trim down to ideal height would have made the horse sore. Subsequent trims every couple of weeks for a month or so will get the heels down to ideal height. Notice, though, the angles of the hoof wall being the same angle as the coronary and the pastern. The toe is nice and short and the hoof has no irregularities. This hoof does not show much arch to the quarters as it is a horse that is kept on soft ground. A horse that is kept on hard ground would exhibit more arching. 

4.   Hooves should be smooth-walled showing no ridges or rings around the hoof. Neither should there be any chips, dings or other evidence of pathologies or injuries.

5. The coronary band hairline should be a straight line when viewed from the side with no bumps or waves. The angle of the coronary hairline, when viewed from the side, should be close to 30 degrees (31 - 33*) to ground level. This allows the coffin bone inside the hoof capsule to rest nearly at ground level. Notice the slight wave in the hoof arrowed whereas the hairline on the other hoof is  straight. The placement of the wave on this hairline is indicative of bars that are left too long and a slight pressure point on the hoof wall.

6. The frogs should be wide across the back of the hoof with a nice, calloused, smooth appearance. (Note: horses kept on wet or soft ground will have a more rubbery, pliant type frog.) When the hoof is weight bearing the frog should be in ground contact. There should be no slits or crevices in the frog which would indicate pathologies.

7. The bulbs of the heels should be uniform in size and appearance.       

   
   
   The photo above shows comments on a REAR hoof. Notice the nice, full frog and heel. It's evenly shaped on both sides.

   The yellow line along the frog crevice show that the line of the hoof from apex of frog to the sides of the heel bulbs is correct for a fully functioning barefoot hoof.

   You can also see the outline of where the hoof naturally falls at the toe. This is a rear hoof so the toe is NOT rockered at all and the overall shape is more oval than the front.

8. In motion at a walk, the horse should be able to be clearly viewed as landing HEEL FIRST with no pronounced "kir-chunking" of the fetlock joint. Long toes on a horse do not allow for this movement. Toes that are left too long will delay the breakover and cause the toes to wear down from the underside faster than the heel will wear down thus causing imbalances that set up a whole gamut of other issues.

9.   There should be no discoloration of the sole of the hoof    indicating bruising, bleeding or other injuries.  The sole, itself, should be approximately 1/2 - 3/4" thick. With a traditional pasture trim, this sole is generally pared away leaving minimized protection for the P3. The sole grows at the rate of about 1/4" a month. Therefore, when a horse's sole is pared down to less than a 1/4 of an inch, as is frequently the case with pasture trims, it will take at least 3 months for that sole to grow back to full thickness and then another month or two to form a strong, thick callused protection. One would expect a horse to be tender on the sole until it is grown back and calloused.

10.  The hooves, in general, should be wide and suitable for the weight and size of the horse.  One can expect that the hooves may grow 1 - 2 sizes after being de-shod and trimmed properly for maximum hoof function.

11. When viewing the hoof "plane" (sole) from above there should be a flat plane with no ridges, bumps or uneven plane. The toe should have a neat "rocker" at a 10 to 15 degree angle from about a thumbs width in front of the frog apex to the outside toe wall. 

12. When viewing from the side, the quarters should be nicely arched so the hoof ground contact points are clearly on either side of the toe and at the heels. When standing, one should be able to slip a piece of paper directly under the toe and then on either side of the hoof.

13. The hoof wall should be nicely rolled all the way around. The extent of the roll will be directly influenced by the type of ground the horse walks on regularly. Soft ground will not wear the walls round as much as hard-rocky ground and hooves on soft ground need more traction to prevent slipping. Hooves on rocky ground will naturally be "flatter" in the sole than horses that live on soft ground. 

14. HEELS  approximately 1/8TH above the live sole at the buttress.
    
                    
    
    Individual hooves will vary as to ideal heel height for that individual horse.  This photo shows proper heel length. Notice that while in a non-weight bearing position the frog is just touching at ground level. This is excellent. When the horse loads that hoof (steps on it), the frog will then be touching the ground and bearing the weight of the step to allow the circulatory pump action of the frog to be effective as well as allow for maximum shock absorbency and dissipation of energy.