Recognizing Foot Imbalances in Horses
Proper foot balance is important to the long term soundness of all horses. Although the appearance of the foot will differ somewhat between horse breeds and the type of activity the horse is used for, there are some basic parameters of foot appearance that apply to all horses.
Generally, the foot should have a symmetric appearance. This applies when the foot is viewed from in front, from the side, and from the bottom when the foot is picked up. The foot being in proper balance is important to how the remainder of the musculoskeletal system functions during locomotion, and is vitally important to performing athletic activities successfully at a high level.
Most concepts of proper foot balance have derived from observations made with the horse at rest. More recently, techniques documenting foot flight and foot placement during motion have allowed for a more detailed understanding of foot balance dynamics to be developed. There are also differences between front and hind feet in both static at rest evaluations, as well as how the foot contacts the ground during motion. For the rest of this discussion we will be referring mainly to the front feet.
Types of Foot Imbalance
• Static (Im) Balance
A horse needs to be standing squarely and fully weight bearing on all 4 feet to properly evaluate static balance. Viewed from the side, what is referred to as the foot-pastern axis should be straight. This means that an imaginary line drawn down the front of the horse’s pastern should continue in that line down the front of the hoof wall. Similarly an imaginary line along the hoof wall at the heel should parallel the line down the front of the foot. From this lateral viewpoint one is evaluating dorsopalmar balance.
If the line down the front of the hoof wall is more vertical (steep hoof angle) than the line formed down the front of the pastern, this conformation is referred to as a broken-forward foot pastern axis. Horses that tend to be ‘clubby’ or have a ‘club footed’ appearance will have this angulation
Of greater concern, especially over the long term, is a foot pastern conformation where there is a low hoof angle and a more vertical pastern angle. This is called a broken-back foot pastern axis.
This type of conformation can put more strain on some of the soft tissue support structures coursing along the back of the horse’s leg. Over time it also is associated with the foot changing shape from a more rounded, to a more oblong shape. This shape change is often accompanied by a narrowing of the heels, and a frog that becomes narrower with an increase in depth of the frog sulci. Clinically this is referred to as the ‘long toe – low heel conformation’. Foot soreness and heel pain also tend to result from this type of conformation over time.
Viewed from in front, an imaginary line drawn down the middle of the metacarpus or cannon bone should also bisect the pastern and the foot. From this viewpoint one is evaluating mediolateral balance.
The hairline at the coronary band should be parallel to the ground and the hoof wall length around the foot should be similar. Deviations in the angle of the hairline suggest uneven foot loading which is commonly seen in the condition called sheared heels. Generally an area of the foot receiving greater load will result in an elevated hairline in that area.
When the foot is viewed from the bottom, it should again have a fairly symmetric appearance with the width and length being approximately equal. A common foot distortion alluded to earlier is the long toe-low heel conformation. With this conformation the foot becomes long and narrow and loses its rounded appearance. The hoof wall at the heels should also end very close to the widest part of the frog. In the long toe-low heel conformation the hoof wall at the heels (which marks the point of ground contact at the heels) becomes situated more forward. This also places undue stress on the foot structures of the heel region, which can result in local soreness and lameness.
One should also learn to identify the widest part of the hoof capsule. In a normal foot, this is generally along an imaginary line drawn across the foot
that intersects the frog approximately 1 inch behind the apex or front of the frog. A black marking pen can be used effectively to actually draw this line and create a greater visual effect. Generally one wants to have a 50%:50% distribution of foot mass in front of and behind this line.
In the long toe situation, more foot mass becomes apparent in front of this line, which again over time is often associated with soreness emanating from the heel region with resultant lameness.
• Dynamic (Im) Balance
Dynamic balance is assessed by watching the horse travel at a walk and a trot, from in front, behind and from the side. Viewed from the side, one likes to see concurrent landing of both heels and the toe (flat foot landing), or even a slight heel first landing. Certainly a toe first landing is undesirable and is often associated with pain coming from the heel region of the foot. Viewed from in front or behind, either the flat foot or slight heel first landing is again desirable, with both heels generally landing at the same time. It is worth noting that some horses will normally land first slightly on the outside or lateral heel of the foot, but rarely will a horse normally land medial or inside heel first.
By making a small number of observations of a horse’s foot, both at rest and in motion, a person can make some deductions about the overall foot balance of that horse. Those observations, coupled with any performance changes the horse has undergone, can help determine if further investigation of a foot balance issue is warranted. Further investigation is best undertaken with both a farrier and a veterinarian, as often sequential radiographs using foot markers are required to obtain the optimal result.