As farriers we spend a lot of time discussing subjects like the weight-bearing phase, breakover, gait abnormalities and normal performance with other farriers, owners and veterinarians. But what do we really understand about those things?

From these terms, weight-bearing is simplest, when the horse stands or moves on its feet.

Then there is breakover. As farriers, we think we know a lot about breakover, as it has been pounded into our vocabulary. I question whether we really understand what it is.

Then we might be able to discuss something about gait abnormalities, but how many of us actually have a handle on the subtle differences between gaits of horses. Mississippi State University researcher Molly Nicodemus earned her PhD on the temporal parameter differences in racking, walking and gaited horses. Definitions are fine, but they lull us into the rut that they are all many of us need to know about them. 

Timing is essential to understanding gaits. It can be measured in total time of the stride sequence. It can be a time measurement of weight bearing, suspension or swing phase. It can also be a factor in determining advanced placement or advanced liftoff. Timing can be differentiated by your ear by hearing the gait on hard surfaces. Remember that  timing is not only determined by factors of shoeing, but also by variables like the horse’s body, rider and the horse’s ability to compensate for lameness or mechanical deficiencies.

Sounds confusing? It is, but let’s explore this a little further. 

Effect of Increased Burden

Dr. Steve Wickler, a researcher from California Polytechnic State University, put horses on treadmills while monitoring their oxygen use. He found that horses have preferred gait stride length and frequency that, when reached, have the most efficient use of oxygen. I think any runners reading this have found a speed at which you run that is comfortable and you can continue for a while. He also found that it takes 50 pounds of weight on their back to measure a change in either the length (shorter) or time (faster frequency) of the stride. Now that doesn’t mean that 25 pounds would not be enough. Instead, it means the measuring equipment couldn’t register that difference until it reached 50 pounds. 

On the average horse of 1,000 pounds, that additional burden of 5% of its body mass is enough to change how it moves. This might also change the way the horse stands too. Sounds simple enough, but what about the addition of a 150-lbs. rider (that is 15% of the body mass). Would that change be linear? Wickler’s research doesn’t explain that. It would, however seem logical that as the weight increases, the ability of the horse to compensate for that change becomes more challenging. I doubt whether the horse would be able to move comfortably with 1,000 lbs. added to its back. Maybe it wouldn’t even stand up.

When we watch horses go from the side, farriers should see things that may be important to us in defining what is a “perfect gait.” Let’s say you are watching a horse trot in a straight line. Not only can you see the synchronized movement of the legs, but you should hear the placement of the feet onto the terrain. You don’t hear the departure of those feet. Ideally, the front hoof should leave the ground before the hind providing for a slight “advanced liftoff” of the fore hoof on the trot diagonal. This is accomplished by front legs lifting the body, allowing the hind feet to have a little more time to push with the hind leg while the other three legs are airborne.

This advanced liftoff also provides time for the front foot to be away from the hind foot (on the same side) when it gets to where the front foot was on the ground. Texts have noted for years that hind foot placement in the ground should be approximately in the same place the front hoof was on that same side. In order for this to happen the front foot cannot be there.

That slight independent push out of the hind leg provides the bump in the saddle that the rider feels at the post.  In addition, the hind leg will swing through the air from that slight push to allow an efficient adjustment in time so that the paired leg placement will be heard simultaneously. 

It is not normal for a hind leg to have advanced lift off at the trot as it will put that hind foot in position to step on the front foot firmly planted in the ground. A common complaint of an early departure in the hind is, “My horse has gotten heavier on the forehand than it was.”

The still from a video recording shows a horse with an advanced liftoff on its front.

In his 1910 book, The Gait of the American Trotter and Pacer, Rudolph Jordan points this out vividly that the best horses had an advanced lift off in the front (Figure 1). That was enough in time that he could see that with the naked eye. Experts believe the human eye sees between 30-60 frames per second. If your eye operates at about 30 frames per second (FPS), that equates to a separation of about 33 milliseconds — enough to be seen by your eye. In Jordan’s era, that difference was greater and harder to see at speed. Of course, high-speed video cameras were not available.

Practically any text that attempts to discuss gaits will likely tell the reader that a horse should put its hind foot in the foot print of the same side front foot. That statement should tell you that the front foot can’t be there when the hind foot gets there.

So, let’s put this information to use on a common problem of farriers. “My horse is scalping, forging, overreaching and/or pulling front shoes off. Can you fix it?” The timing of the separation of the hinds from the fronts that distinguishes those gait problems from one and another. If you visualize the front foot on the ground at just about heel lift, and the hind foot is coming in early, it overreaches and hits the heel bulbs. If the hind hoof is a little later when the front heel lifts and exposes the heels of the shoe and is then hit by the toe and pulls shoes. A little later still, the front hoof is airborne with the toe being exposed and the hind foot hits the ground side of the shoe at the toe. Now you have forging. If the hind foot is a little later and sliding under the front hoof hitting of the coronary band on the hind foot, that is scalping. 

What Can You Do?

I’ll ring your common sense button:  the front foot can’t be hit if it isn’t there. These gait problems are well-defined, but they all have one thing in common: timing. Sometimes the fix is straight forward, other times it might take some careful analysis to put your finger on what is happening. Also, will the solution required be compatible to the discipline the horse is doing, as well as acceptable by the owner or trainer? They are quick to protest if the fix just doesn’t look right to them.

This image shows a dressage horse with slightly advanced liftoff on its hind.

If we take that forging or over reaching horse and video it at 240 frames per second will give you about 4 milliseconds per frame of time. In my experience, these horses all have advanced liftoff in the hind as the primary problem (disregarding lameness in front). Figure 2 is a horse with just slightly advance lift off behind, quite possibly since it is barefoot behind). That is understandable as the way horses are shod today with the hind feet barefoot or considerably backed up. 

For example, one performance horse that I watched was so far out of time, the hind left the ground 16 frames (240 fps=64 milliseconds) before the fronts. The horse would have to hesitate with the hind leg in the air to allow it to sync with the diagonal front leg to hit the ground concurrently. That costs the horse energy and efficiency in propulsion and of course becomes an overall performance deficit. That 64 milliseconds is important, but now add another 33 to it to reach advanced liftoff in front. Now the horse is  of a second out of dynamic balance and efficiency.

Video-based interpretation takes time in the field. Videoing should be done with the horse doing what it is intended to do. It should also be done without anything covering its feet or altering gait (even boots should be avoided). You would like to see the horse in its natural state. This affords farriers the best authentic information to deal with. The next question comes from that information and how do we coordinate it into a plausible way to correct the problem?

The goals, of course, would be to slow the hind end and speed up the fronts. By how much and doing what? That is where you come in. Your skills as a farrier, your knowledge of gait and timing is important to resolve the issue. Think hard about the changes you make and how they effect the weight-bearing phase. Judicious use of traction, rocked toes, pads, wedges, angle changes, toe length changes are all items in your toolbox that can be utilized if skills and knowledge are available to apply them.

It is obvious in Figure 2 that the timing changes by shoeing would be insignificant compared with what is required to fix the 64 millisecond early one behind. You will have to discuss this with the client, explaining why it needs to be done. Of course, some breeds have shoeing rules that have to be adhered to as well.

It is often helpful to also use the slow motion video to assess the canter. The canter is a three-beat gait with the lead leg (hind) being the opposite of the direction intended. That is the left hind leg is the lead leg for the right canter lead and the right hind leg is the lead leg for the left canter lead. The sound of the canter is a steady equally separated cadence of three beats. The first beat would be the impact of the lead leg, second beat would be the diagonal set of legs (landing squarely) and the third beat is the trailing leg as it impacts the ground. Counting the frames between these impacts can assist you in determining if the diagonal is closer in time to the trailing or lead leg. Being closer to either leg can be attributed to necessary shoeing changes or may be compensation of lameness. 

Gait deviations evaluated by time can be attributed, among other factors, to shoeing deficiencies and rider. It is possible that if there is a timing discrepancy in the trot departure times on a diagonal, that same diagonal could be off during the canter. A farrier’s clinical evaluation of mechanical discrepancies between diagonal and contralateral legs should be accomplished. The veterinarian should perform a lameness evaluation.

Perhaps you think I am being hyper-critical. However, on a high-level performance horse, competition standards are so challenging that these minor discrepancies will play a role in whether the horse finishes first or last. This is regardless of the breed or discipline.

To give you an example of how little this basic understanding of timing is construed by the modern day horse industry, here’s another example. Recently, the Arabian Horse Association changed rules in regards to shoe width (now 1- and -inch thick, plus pad and wedge). Shoeing practices don’t make them toe weights — most shoes are left full width into the heels to have as much weight as possible while at the same time leaving a short hind foot and a light shoe or barefoot. The added heavier shoe and package makes it harder and later on departure of the front foot and the hind foot hasn’t been changed to adjust its timing. This has made it nearly impossible to keep shoes on, so now they added a rule allowing the use of bands to help heel shoes on. Ah, common sense at play.

The temporal parameters of the weight-bearing phase and how shoeing techniques alter them is important knowledge to have. How these techniques interact also is important as they might effect force application or dissipation, timing of liftoff or placement or swing phase time. A simple example would be raising the hoof angle. This equates to altering the forces of acceptance and application in the distal limb soft tissue, Time to mid-stance (shorter), time of weight-bearing (shorter), time from mid-stance to lift off (shorter), lower and altered swing phase arc of travel, longer time in the air (especially if the hind hoof angle was not altered), heel-first placement into the ground, to mention a few.  

Gathering the information on a gait problem and formulating a methodology to mitigate that problem is just another skill farriers must have in their tool box to help the horse. Until mastering this skill, then the farrier’s answer remains, “Let us just try this and we’ll see what happens.”