July 29, 2013 by worcsfarrieryservcies
Here is an essay on static hoof balance I wrote for my degree course last year, We used a specific reading list and had to look at similarities and differences of opinion
The importance of hoof balance has long been documented, there are references dating as far back to the third century BC about the importance of good hoof balance. Williams and Deacon (1999) wrote ‘Good foot balance is achieving a foot which is of a shape and strength to support the weight of the horse whilst providing a base for optimum movement.’ This then ‘keeps a balance between the extensor and flexor muscles and evenly distributes the strain on all structures’ Emery,Miller,Van Hoosen (1977.) Turner (1992) also states that ‘Balance is defined as harmonious adjustment of parts – the equal distribution of weight over the foot. Stashak (2002) writes ‘Static (geometric) balance refers to a geometric equilibrium of the limb and the hoof in the standing position.’
The importance of static hoof balance
Hoof balance is considered very important to keep equines sound. Williams and Deacon (1999) states ‘that up to 95% of all horses have some form of foot imbalance which predisposes them to injury.’ ‘If your horse is lame you have a three-out-of-four chance of improving or eradicating that lameness simply by paying scrupulous attention to the balance of his feet.’ If the horse is unbalanced in the hoof then very quickly they can become susceptible to lameness or musculo-skeletal disorders. ‘Some of the common problems that might be attributable to faulty foot balance include:
Turner (1992) says there are six hoof balance abnormalities, which are commonly seen in horses.
- ‘A broken hoof axis exists when the slopes of the axis are not the same
- Under-run heels have been defined as angle of the of 5 degrees less than the toe angle
- Contracted heels was defined as frog width less than 67% of the frog length
- Sheered heels was defined as a disparity between the medial and lateral heel lengths of 0.5cm or more
- Mismatched hoof angles
- Small feet (feet too small to body size) was defined as a weight to hoof area ratio of greater than 78 pounds per square inch’
All of these conditions affecting balance could have a compromising affect on the horse’s anatomy, which could lead to one of Butler’s pathologies listed above.
‘Feet that are kept balanced are seldom lame. It is a well established fact that the majority of foot and leg diseases are caused or aggravated by unbalanced feet.’ Butler (2005)
How to assess static hoof balance
Hoof balance should be assessed, by looking at the horse stood on a flat and solid surface. The horse should be stood as square as possible. By drawing reference lines through the limb we can assess symmetry and proportion. ‘The limb is a three dimensional object. As such it has three axes X, Y and Z Butler (2005.)
The X-axis is assessment of medio-lateral balance. We assess this by looking at the hoof from the front. Also by picking up the limb and letting it hang freely looking down the bone column we can assess it from the back.
‘When viewed from the front, the medial and lateral hoof walls are equal in length, and the coronet is parallel to the ground’ Stashak (2002) ‘Medial/Lateral balance can be assessed by both hoof measurements and by radiographic examination’ Turner (1992). Turner also states ‘Hoof related imbalances will show medial/lateral hoof length disparities.’ The use of a T-square can be used to compare heel height in relation to the long axis of the limb. This can be an invaluable tool especially for training your eye to see balance.
Hickman & Humphrey (1988) show medio-lateral balance of the forelimb by drawing ‘a plum line from the point of shoulder divides the limb into two equal parts’ and of the hind limb ‘a plum line from the tuber ischii should divide the limb into two equal parts.’
It is a common theory in publications that for the foot to be balanced it should be of equal proportions to the mid line of the hoof (meaning the hoof wall to be of equal lengths medially and laterally.) With the hoof being square to the long axis of the limb.
However in a difference of opinion Emery, Miller & Van Hoosen (1977) say ‘Medio/Lateral balance does not necessarily require that the wall on both sides of the hoof be of the same length.’ There theory is that as long as the ground-bearing surface is square to the long axis of the limb the foot will be balanced. Which contradicts Turner (1992) who states a disparity between the medial and lateral heel lengths of 0.5cm or more is a sheered heel and so unbalanced.
The Y-axis otherwise known as cranio-caudal or dorsal- palmar/plantar is viewed from the medial and lateral aspects of the horse. When looking at the Y axis hoof balance ‘the three digital (foot) bones form a straight line’ Emery, Miller & Van Hoosen (1977.) Stashak (2002) agrees saying ‘The angle of the hoof is considered correct when the hoof and pastern are in alignment.’ He goes on to say ‘ The goal is to align the dorsal surface of the coffin bone with the long pastern bone axis.’ Both Stashak (2002) and Turner (1992) agree that ‘when the heel angle is 5° less than the toe angle the hoof is said to have under-run heels
It is the view of many publications that the hoof wall should be straight running parallel with the phalangeal axis. Opinions of this angle are varied. Stashak (2002) states that the forelimb hoof pastern angle HPA is between 53-58°. But Turner (1992) states that forelimb HPA averages 48-55° Turner (1992) also observes that ‘the heel length should generally be about one- third of the toe length.’
It has been noted that the horses HPA mirrors the angle of the horses scapular ‘A line from the crest of the withers through the point of the shoulder is almost always parallel to the anteroposterior hoof axis’ Emery, Miller & Van Hoosen (1977)
Looking at the foot from above or below assesses the Z-axis otherwise known as Hoof Form balance. ‘From below, visualize a symmetrical hoof form around an imaginary dot about one-half inch back from the point of trimmed frog.’ Butler (2005.)
Stashak (2002) also refers to this point in the center of the foot as ‘Duckett’s dot.’ He states ‘Dukett’s dot is located 3/8 to ¾ inch back from the tip of the trimmed frog.’ This dot not only symbolizes the center of the foot but also is a reference point for locating the center of articulation of the coffin joint.
You can asses Z axis balance from above by looking over the top of the hoof with ‘the position of the circle of the coronary band within the circle of the hoof’s perimeter. Ideally, the circles should be concentric, one within the other, symmetrical distances apart.’ Butler (2005)
How To Correct Static Hoof Balance
Static hoof balance can be compromised easily, causing the hoof to become unbalanced. There can be a number of different factors leading to an unbalanced foot, it is a farriers job to 1st assess the horse to establish what sort of imbalance the horse has, and 2nd to find the route cause of the imbalance and try to create a shoeing plan to help improve or correct to the ‘ideal’ form.
Many imbalances can be corrected by trimming alone, if the medial/lateral balance is out the use of a T-square can help to identify the high heel and you can trim accordingly. If the imbalance has been caused by an angular deformity further up the limb then more may be needed than trimming alone. The trim is always the starting point of correction but sometimes a shoe is needed. ‘Simply trimming the foot parallel to the bottom of the coffin bone and dressing the foot parallel to the sides of the coffin bone cannot solve some limb deformities. It is necessary to extend the shoe base towards the limb’s centre of gravity.’ Butler (2005).
There are many different factors, which affect hoof balance. From looking in these publications it is also apparent that there are some differences on what ideal static hoof balance should be. However the general consensus is that if you use three different planes for assessment X, Y and Z (Medio/lateral, caudal/cranial and proximal/distal). The aim is for symmetry and geometric proportion, around imaginary plum lines and reference points. With a trained eye you can assess static hoof balance and from there continue your assessment onto the dynamic stage before concluding the information gathered and creating an individual shoeing plan for the horse.
Butler, K. D. (2005) The Principles of Horseshoeing 3. Butler Publishing. Maryville. Missouri.
Emery, Miller, & Van Hoosen, (1977) Horseshoeing Theory and Hoof Care. Lea and Fabiger. Philadelphia.
Hickman, J. & Humphrey, M. (1988) Hickmans Farriery. J. A. Allen, and Co London.
Stashak, T.S. (Ed.) (2002) Trimming and shoeing for balance and soundness. In: Adam’s Lameness in Horses, 5th edn., Lippincott Williams & Wilkins, Philadelphia. pp 1110-1113.
Turner, T.A., 1992. The use of hoof measurements for the objective assessment of hoof balance. Proceedings of American Association of Equine Practitioners 29, 389–395.
Williams, & Deacon, (1999) No Foot No Horse. Kenilworth Press Ltd. Buckinghamshire.
Written by Matthew Burrows of Worcestershire Farriery Services