Spectrum of Usability

The spectrum of usability is a rating system used to determine how a horse can be worked without causing injury to the feet.

The spectrum of usability scale goes from one to ten.  The following list gives an idea of the kinds of activities which can be performed at each level of the spectrum:





1. No hand walking
2. Hand walking / Ground work
3. Light riding in a ring
4. Ring work / Light trail riding; no uneven surfaces
5. Backyard horse / Trail riding walk; over uneven surface
6. Backyard horse / Trail riding able; to trot on uneven surface
7. High level Dressage / Jumping on prepared surface
8. Reining / Eventing / Endurance 25 - 50 miles
9. Endurance 100 miles
10. A perfect foot

Exceeding the level of work indicated by the spectrum of usability can lead to any or all of the following: abscesses, flaring, cracks, and development of improper compensating structures.

Most horses that have not had much conditioning or have had shoes recently removed will be in the range of three to five.  Some horses will naturally have good feet and there may be a few of these in the six to seven range.  For most horses to improve the feet above a five on the scale, it is going to take a systematic conditioning program.

The parts of the horses foot that are rated are as follows:

1. Frog
2. Sole
3. Heel (angle of the bar)
4. Bars
5. Wall - white line, inner wall, and outer wall from forward of angle of the bar to the toe, from ground to hair line
6. Toe - white line, inner wall, and outer wall from ground to hair line in toe area.
7. Lateral cartilage and digital cushion

The following list outlines what to look for when rating the spectrum of usability for a horses foot:

Frog - Good proportion.  This means not narrow and contracted or overly flat and wide.  The frog should slope from apex to widest point at about a five degree angle.  The frog should have a well defined open central sulcus.  The frog should be free of infection.

Sole - The sole should be smooth.  It should have concavity with the deepest point of concavity being the apex of the frog.

Heel (Angle of the bar) - The heel should have adequate surface area.  The outer wall should be thin.  Most of the surface should be inner wall.  There should be a good connection to the bars with no gaps in outer wall or inner wall.  The back part of the heel should be even with the widest part of the frog.  Proper height.  The height should be about one sixteenth of an inch above the frog at its widest part.

Bars - The bars should be straight extending to about the mid point of the frog.  The outer wall should be thin with most of the bars made up of inner wall.

Wall - The wall should have a reasonable amount of outer wall and a thick inner wall.  There should be no cracks.  There should be no infection in the inner wall or white line. The white line may be worn away some.  The wall should not flare, but be straight from just below the coronet band to the ground. The angle that the wall makes with respect to the ground should be close to vertical.

Toe- The toe should have a thicker outer wall and a thick inner wall.  There should be no cracks or signs of infections in the inner wall or white line.  There should be no flare.  The toe should follow a straight line from just below the coronet band to the ground.  The shape of the toe at ground level should be symmetric to the curve of the coronet band.  The toe plane should be even with the heel plane.

Lateral cartilage- The lateral cartilage will wrap tightly around the digital cushion.  The outer thirds of the heel bulbs will be covered by lateral cartilage.  The heel bulbs should have reasonable height (neither flat nor club).

Having looked at each of these items the ratings are developed in the following manner.

A rating of one or two is given when a structure is very weak or significant parts are missing.

A rating of three or four is given for structures that are all present but not in good condition.

A rating of five or six is given to structures where shapes and proportions are correct.

Ratings of seven and above are relatively rare and indicate that structures are in excellent condition with correct form and above average condition.