My experience is primarily with gaited horses. With Walkers that usually means a lateral gait, sometimes a centered gait, seldom a trot. When we moved to the Marchadors in 1999 the world changed significantly, as within Marchador breed three ways of going are recognized: the marcha batida, a broken trot; the marcha picada, a stepping pace; and the marcha de centro, a centered gait akin to the way of going of a Walker from the 1930s. My experience with solely diagonal gaits is limited. But I’ve seen a broad spectrum of ways of going.
The process of movement in the horse begins with their gait. When a horse starts to move the sequence of events at the foot is loading, break-over, takeoff, flight, and impact. It’s the same for faster gaits, but just where loads wax and wane vary. There are also some differences between the trotting horse and the “soft gaited” horse. The primary sequence, however, remains the same.
The optimal method of achieving a “show gait” is to breed for it. A good horse begins in the breeding shed. But this process has difficulties. I’ll not spend any time discussing them as I presume any knowledgeable horseman knows about the “genetic lottery.” This means that it’s not uncommon to have a horse with excellent conformation and a winning temperament that might be lacking in way of going. So the owner engages a trainer to address the deficiency. One of the more common ways to alter the way of going in some breeds is the use of devices to enhance “action.”
If a horse does not show enough “flight” in the way of going this can be addressed in at least three ways.
First, lower the angle of the foot. This will mean that it will take more energy to get the foot off the ground and that excess energy will translate into longer “flight time.” Trimming will do this and is commonly used. But for a “blue ribbon” performance it won’t be enough. So the farrier will add a stack of pads, usually leather, that artificially extends the toe and allows for an even lower angle. That means even more energy at break-over, which would translate to longer “flight time.” That’s the purpose of pads. They are not there to absorb concussion or provide any sort of “therapeutic” benefit.
Next, the farrier can alter the shoe type used. Adding weight to the foot will require more energy input for break-over and takeoff. Make a paper airplane and launch it. Note how it flies. Now add a paperclip to the nose and note the difference. That’s the impact of adding weight.
The third item would be some sort of “bracelet” around the foot that would cause the horse to try and “step out” of an irritation or “flinch” at the imposition of pain. These are separate and distinct actions. They may or may not be used together.
Can any of these devices, by themselves, cause a horse to be “sore” in the meaning of the Proposed Regulations? The answer is “yes.” The least likely item would be a light, plastic chain. The most likely to would be the stack of pads. Indeed that device would also be the most likely to cause long term injury. Of course rarely are these three strategies used separately; they are very commonly used together, where their impact is magnified, to the detriment of the horse.
So far all we’ve looked at is what’s happening from about the pastern on down. That’s bad enough, the long and low angle altering the anatomically correct alignment of the lower leg which ought to be a straight line, not a broken lever. But now we have to consider that there’s a 1000 pound horse moving over that foot which is stuck to the ground at speeds from 4 mph to 20 mph. That’s a fair amount of energy applied to the foot under normal circumstances. If we’ve weakened the structure of the foot with a mal-formed angle by applying a device what will be the consequences? Or is it the position of the advocates of devices that there will be no adverse consequences? I’m not aware of any credible studies one way or the other. But there is credible work that a mal-formed angle IS detrimental to the long term soundness of the horse. Here is one reference http://equipodiatry.com/article_proper_physiological_horseshoeing.htm Here is another http://www.horseinfo.com/info/faqs/faqconformQ6.html The hard truth is that the stack of pads used to alter the anatomical correctness of any horse will, over time, cause injury in the vast majority of horses. There will be some who break down early and some who show little to no functional effect. That’s just because horses have different DNA and different lives. But it’s going to be there.
I could not find anything discussing the effect of adding weight directly. But it’s well accepted at adding weight will affect the kinetic performance of the foot. It is certainly the practice within disciplines that reward the “high step” to add weight to gain a competitive advantage. I did find the following that is relevant to the issue. It question is aluminum vs. steel shoes, but the issue is weight differential. It’s long and not all parts are relevant to this discussion but it’s a worthwhile read. http://www.ads.uga.edu/documents/ElodieJEVS-D-11-00083R1-1.pdf
The chain is used to encourage the horse to pick up the foot higher, either by causing a “step out of something” action or a “flinch” due to the chain striking the sensitive coronary band area upon impact. I could find nothing that actually addresses the use of the chain except the previously mentioned Auburn Study. In any event the chain works because it irritates the foot of the horse. The users of the chain know this. They claim it “trains” the horse but they also acknowledge that if you remove the chain the “training effect” quickly dissipates. That suggests to me that there is, in fact, NO training involved, just the infliction of pain (or, if you will, “distress”) and that the “trainer” who does this is benefiting from a “memory of pain” response by the horse.
Some claim that this is no different that use of a spur or crop to induce a response. I disagree. The spur is applied by a competent trainer to either add authority to a natural aid, the leg, or to “discipline” a failure to comply with a command. The crop allows the trainer to extend their reach and touch the horse to induce a movement. It also has a disciplinary function. Each device is used as required but not used if not required. It takes conscious thought by the trainer on both when to use the device and how to use the device and when to cease using the device.
A chain around the ankle of the horse is not training anything because it is always “on.” The horse is irritated by the chain and performs a desired movement. The chain continues to function. The horse is irritated by the chain but doesn’t perform the desired movement. The chain continues to function. Whether the horse is compliant or not the chain is banging away on the coronary band. This is the antithesis of training.
Now that we’ve seen how each item works individually do we really need to spend much time talking about their combined effect?
The Proposed Regulations would consign “action devices” to the dustbin of history. IMO that’s where they belong. An awful lot of vets agree. The people who would fight to retain these devices have their own opinions and that’s OK. But I believe I’ve demonstrated that they are deleterious to the long term health of horses individually and even more so when used in combination.
G.