A while ago, my attention was once again drawn to a typically poor article on theHorse.com. Not unusually, this is an article about feet and, also not unusual, it is written by a vet and contains citations by other vets.
Many people will obviously start to say that 'the vet will know...' so why criticise - but there lies the crux, the vets clearly don't know. The problem lies in the fact that vets are first and foremost biologists - or at least veterinary education is centred around biology with a fair bit of chemistry thrown in. This does have a sound reason; the daily work of a vet is being involved with biological processes and their associated chemical reactions. The latter being aided or modified by often symptom specific drugs. But the mechanical side of things is much less well represented. Particularly when it comes to the limbs. Veterinary science finds itself still stuck in the Middle Ages with techniques and theories that were not even conceived by vets! And this latest article on theHorse.com just underlines the case once more.
The article How Healthy Horse Hooves Help Arthritic Joints by Nancy S. Loving DVM dates from October 2018.
Dr Loving is aided in her article by comments by Andrew Parks, a university professor of veterinary medicine, and Steve Kraus, farrier and instructor at Cornell University of Veterinary Medicine...this last is typically laughable. To have somebody who advocates the nailing of overweight pieces of metal to an animal's feet being the resident of a university of veterinary medicine should be a major embarrassment.
When offering arthritic horses relief, start from the ground up
The degenerative joint disease arthritis is all too common in active and aging horses. In an effort to slow the progressive deterioration of joint tissue, owners and veterinarians often reach for anti-inflammatory medications and/or regenerative therapies. After all, our goal is to keep these joints comfortable.
One often-overlooked strategy in this effort is hoof care. Certain trimming and shoeing techniques can alter a horse’s limb biomechanics—for better or worse. In this article we’ll discuss how to care for arthritic horses’ hooves for maximum comfort.
As with much of veterinary medicine, this article starts immediately with a treatment rather than with prevention.
If we were to prevent, or at least do what we can to prevent, the onset of a disease –in this case arthritis– then our horses would be in a much more favourable situation. And with many degenerative diseases, prevention or delayed onset is not so difficult to achieve. For the horse, adequate management can mean the difference between a full and comfortable life and a short painful one.
Arthritis is indeed common in active and ageing horses but its roots lie not so much in the age, nor the activity, of the horse but rather its (mis)management. A shod horse is far more likely to develop arthritis than an unshod one, as the article briefly explains. The combination of horseshoes with inappropriate activity will exacerbate the problem and the longer the horse is exposed and thus the older it is, the more severe the problem will become.
The equine world, professional, amateur and veterinary, is very reliant upon the pharmaceutical industry and as the author of the article says, '...owners and veterinarians often reach for anti-inflammatory medications and/or regenerative therapies...'. All too frequently, the anti-inflammatory medication will be one or other proprietary variant of phenylbutazone –a medication so widely abused that if it was in human medicine, a vast number of doctors would have long been struck off the register. Phenylbutazone is indicated exclusively for chronic laminitis.
Quite correctly, the author indicates that hoof-care is an often overlooked strategy. But clearly, even in this early paragraph, has little grasp of the biomechanical consequences of shoeing and trimming.
What Exacerbates Joint Pain?
Arthritic horses try to minimize their joint pain by reducing the load on the affected limb(s) and shortening stride length. “This suggests that pain is associated with the concussion of impact and extreme ranges in motion (ROM),” says Andrew Parks, DVM, Vet MB, MRCVS, Dipl. ACVS, a professor at the University of Georgia’s College of Veterinary Medicine, in Athens.
Professor Parks explains the problem fairly well here. So why can't he follow up on it with a logical, mechanics-related, conclusion?
Force of impact
The limb’s loading rate (deceleration) when the foot lands affects the force of impact on that leg, as can footing type. “The impact of baked clay in summer or frozen ground in winter is quite different from a soft dirt paddock, bedded stall, or engineered arena,” says Parks. “Anything that slows down the rate of deceleration of the foot is likely to decrease the effect of impact. Materials that absorb energy on hoof landing—either from the ground surface or within the shoeing apparatus—also reduce impact.”
This is actually a bit nonsensical. It is rather typical of the biologists reversed view of mechanics!
It is not the loading rate that affects the force of impact on the leg, it is quite the reverse. The force of the impact –kinetic energy– is the product of mass and velocity. The speed with which this force is dissipated is the deceleration. This dissipation of energy will be found on both sides of the impact point (remember Newton's third law: When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body.) and, as Professor Parks points out, will be affected by the hardness of the surface landed upon. Where he misses a beat is in his assertion that the shoeing apparatus will reduce impact.
The addition of any extra weight to the distal point of the limb will by its very existence increase the kinetic energy of the limb. So immediately we must build-in yet more absorption to compensate for the extra weight...whereas the foot in its lightest form will be able to work together with the tendons, muscles and leg-articulation to create the optimum absorption of impact.
Range of motion
You’re probably already familiar with this concept: Your veterinarian maximizes a joint’s range of motion when he or she performs a diagnostic flexion test to pinpoint soreness in a painful joint. Excessive flexion or extension/dorsiflexion (backward bending or bowing) can aggravate arthritis.
Owners and farriers should handle arthritic horses’ legs with care. “Check range of motion and flexion ability, and don’t force an arthritic horse to bend or flex its limbs beyond its comfort zone,” says Steve Kraus, CJF, resident farrier and instructor at Cornell University’s College of Veterinary Medicine, in Ithaca, New York. “Use of a foot stand (when trimming or shoeing) keeps hind limbs low and supports the front legs to provide better comfort for both horse and farrier.”
To modify or limit range of motion extremes in locomotion, Parks recommends farriers help the foot lift and roll over (called breakover) more easily. “This may mean not only rolling the toe but also the whole perimeter of the shoe and even the heels,” he says. The easier it is for the horse to lift his heels off the ground, the less dorsiflexion the foot will experience at breakover.
Kraus is right, the limb should not be flexed beyond the comfort zone – ever. It is one of the frequent tests when purchasing a horse to flex the leg and hold it in position. If the horse then limps, there is supposedly something wrong (...but you try walking after forcing your leg into an uncomfortable position for any length of time!).
This is all sound common sense - apart from '...rolling the shoe...' We don't need a shoe; in fact, we MUST NOT shoe – even less so in an arthritic horse. The shoe will by definition add length and depth to the hoof; this in itself exacerbates the problem demanding rolling of the shoe. Losing the shoe removes this and all other problems in one fell swoop – and if the horse is still having 'rollover' problems, then there are two solutions: walk the horse on hard –preferably even– surfaces for a short while every day or, if that is too much effort, add a so-called 'Mustang roll' (or simply trim the toe shorter).
Acutely imbalanced horse hoof
Hoof balance is key to keeping an arthritic horse comfortable. Create a more level landing surface by picking out gravel and other debris from hooves daily. Have the feet trimmed every four to seven weeks (depending on hoof growth rate) to help balance the hooves and reduce the horse’s risk of developing long toes and collapsed heels, which can make him more likely to stumble.
“Farriers can manage the hoof capsule with trimming and shoeing to provide proper limb alignment so that forces are distributed equally through the joints,” says Kraus.
If a foot is acutely imbalanced (say, for example, one side has been wedged or trimmed shorter than the other), the joint on the elevated side of the hoof will narrow—something that’s visible on radiographs (X rays) taken immediately following this practice. “However,” says Parks, “if you look at feet with obvious (chronic) coronary band asymmetry and hoof imbalance, an interesting finding is that the imbalance in the joint space usually is not evident on radiographic images.”
This compensatory phenomenon is related to the coffin bone’s movement relative to the hoof capsule. The hoof’s growth rate also changes, slowing on the side experiencing the greater load.
Parks reminds us that the same principles that encourage bone remodeling might also apply to other tissues. Overloading on one side of the hoof might, in fact, slow the rate of cell replication in the coronary band on that side.
“If the hoof wall is imbalanced side-to-side (uneven hoof wall height between medial and lateral—inner and outer—sides), then theoretically, unequal overload stresses can create degenerative joint disease (DJD),” says Parks. “However, a horse’s natural compensatory hoof mechanisms tend to minimize changes within the joints. You may have appreciated how quickly the hoof capsule changes shape once a horse shoe is removed—usually within 24 to 48 hours.”
That said, he points out that if mediolateral imbalance within the foot’s internal structures persists, a horse can develop DJD. Uneven forces place undue pressure on joint components, especially cartilage, which can then create or exacerbate joint deterioration and arthritis, adds Kraus.
Genetics and/or inappropriate trimming can also create dorsopalmar (front to back) imbalances, which affect the hoof-pastern axis (when correct, the front hoof wall should be parallel to the pastern angle).
Here we descend into the mythical world created by the farrier and carried on by many a barefoot 'specialist'.
Kraus' claim that 'farriers can manage the hoof capsule...to provide proper limb alignment...' is typical of the bilge peddled by this dubious profession and, sadly, believed in all sincerity by a poorly educated veterinary community. There is absolutely NO WAY that a farrier or a barefoot 'specialist' will ever be able to sight up a hoof and limb and 'correct' or 'compensate' for so-called imbalance. For a start, a study some years ago –sadly now lost to the mists of time– showed that farriers were incapable of reproducing treatment during successive visits in around 80% of cases. This is not at all surprising since the hoof is a dynamic structure that the farrier 'analyses' in a static situation; the problem is further exacerbated by already present shoes, where applicable, and by the absence of knowledge of what exactly is the horse's conformation.
Even X-ray photographs cannot give an accurate representation since the foot and leg is always in an 'artificial' situation – the horse will never be standing in absolutely perfect balance. Furthermore, as most veterinary surgeons will tell you, often that which is causing pain or discomfort is that which cannot be seen on the X-ray.
In the end, only the horse can correct its stance and its foot conformation. The easiest way to achieve this is to simply trim the hoof adequately and allow the horse to walk on a hard surface like concrete or tarmac to achieve its own personal 'balance'.
Long Term Imbalance
When trimming and shoeing for balance, one of the farrier’s main goals is to make sure the foot is placed properly beneath the skeletal column, says Kraus. “Caudal (rear) heel support relies on supporting the heels in their proper location beneath the leg,” he says. “This support is important to minimizing arthritic discomfort. As the hoof first strikes the ground, the heels act as a fulcrum. If positioned too far forward under the limb, the leg tends to rock backward on that point of the heels. The horse must exert muscular force to overcome this, which strains the joints. Proper heel support requires trimming the hoof to the widest, highest, rearmost area of the frog. If that cannot be done, it is possible to provide support with shoeing.”
To align the heel properly, farriers usually fit the horse with an appropriately sized shoe that increases the hoof wall’s surface area contact with the ground, says Kraus. This prevents rocking back on the heels or sinking into soft ground, either of which stress joints whether they’re arthritic or healthy.
Farriers might apply egg bar shoes to horses with low-angled, underrun heels, says Kraus. “Caudal heel support from the bars (found at the rearward ends of the hoof wall) reduces backward sinking of the hoof, while also providing a greater bearing surface to spread out the horse’s weight,” he says.
Parks says elevating the heels has been shown to alter the distribution of pressure in the coffin joint, which could potentially increase wear and tear.
“The ideal relationship between the pastern and the hoof is when the dorsal (front) wall of the hoof is parallel to the dorsal pastern, and if the foot is trimmed so that this relationship is not parallel, it has the potential to increase the overall force on the foot during the course of the stride,” says Parks. “Additionally, a long toe increases the lever arm at breakover, which increases the force required to lift the heels off the ground. These phenomena exacerbate arthritic pain in the distal (lower) joints.”
Kraus adds that when horses strain to move their lower limbs and break over a long toe, they can aggravate low or high ringbone (coffin or pastern joint arthritis).
Once again, the farrier descends into nonsensical theorising. Talk of '...aligning the heel properly...' and '[applying] egg bar shoes to horses with low-angled, underrun heels...' just goes to show how far from reality these people are. As already explained above, the farrier –indeed, any external agent– will never be in a position to 'align the heel properly'. Anybody claiming this is a fraud and if you believe him, you are doing yourself an injustice. Three years of farriers' school, even with a nice diploma at the end, is not an indication of competence; it is an indication that someone is trained in middle-age thinking and practices.
Underrun heels need to be treated, not compensated for. They need correctly trimming to remove the underrun, not the addition of egg-bars to raise the caudal section of the P3. This is nothing more than bone-idleness on the part of the profession and ignorance on the part of the individual farrier.
Smart Trimming & Shoeing Techniques
Backing up the toes
Many farriers attempt to correct a long-toe, low-heel hoof configuration by setting the shoe back at the toe. While Parks says this improves breakover for the short-term, leaving the toe hanging too far over the toe of the shoe means the wall at the toe is not in direct contact with the shoe. Therefore, it receives less mechanical stimulation than the wall that is in direct contact with the shoe from the toe-quarter junction (pillars) to the heels. “This affects the way the wall grows,” he says, reminding us that the wall under greater stress will grow slower and vice versa. “Biofeedback tries to restore a previous state,” he says.
Kraus says farriers often apply rocker or rolled toe shoes to horses with arthritic conditions. “These shoes artificially shorten the distance and, hence, the leverage in front of the center of rotation on the foot beyond what can safely be trimmed away,” he says. “Sound, properly trimmed horses need normal toe length for optimum propulsion, but horses with arthritis in their lower joints do better with less-than-normal leverage (i.e., shorter toes).”
Parks says he’s a fan of rocker and roller shoes but warns against removing too much dorsal hoof wall in the shoeing process. “If the farrier uses a rasp to gradually thin the wall at the toe, it may not change hoof wall growth, provided enough stiff wall (the outer one-third to one-half of the wall) is left in contact with the shoe,” he says. “In contrast, if the toe wall is chopped away at a 45-degree angle, while this may ease breakover so that the dorsal wall isn’t in contact with the shoe, it isn’t under as much stress as the adjacent wall. Therefore, on the reasonable assumption that wall under less stress grows faster, the toe will outgrow the adjacent wall, thus changing the conformation of the foot, which may add to arthritic pain.”
One thing that we can clearly add is that the hoof wall is NOT the weight-bearing structure of the foot. It is therefore of little importance where the shoe is affixed, forward, backward, it will always be in the wrong place, transferring the weight of the horse to the hoof wall and thus through the delicate laminae which can easily be demonstrated as not being designed for such use.
The growth of the hoof wall is not slowed but rather stimulated by 'stress' or, as it can also be termed, 'use'. This is readily demonstrable in any horse that has the good luck to be barefoot; intense use does not wear down the hoof but rather stimulates its growth. Again, a farrier's fable that the unshod horse will wear its hoofs out working on hard surfaces.
With arthritic horses, it’s a delicate balance between slip and grip.
Steve Kraus, CJF
Protecting the hind limb
Most shoeing practices only have a direct effect on the lowest limb joints—the coffin and pastern joints. However, farriers do attempt shoeing strategies to influence higher joints, such as using lateral extensions or egg bar shoes on the rear hooves of horses with distal hock arthritis (bone spavin). Kraus says a lateral hind shoe extension provides support to prevent a base-narrow horse’s hocks from rotating outward, while an egg bar shoe might reduce excessive hinge motion that otherwise stresses hock joints.
Study results, however, show that neither rear-foot lateral extensions nor egg bar shoes have a significant effect on stabilizing affected hock joints.
Then there are trailers (or caulks) on hind shoes, which some veterinarians and farriers argue against using because they can cause a foot to stick and torque the joints. Their use, however, often depends on the equestrian activity and terrain conditions.
It can be very regularly demonstrated that the shod horse suffers from shoeing right up the legs and into the shoulders, the hips and ultimately the back. Therefore it cannot be said that the application of shoes does not just affect the distal structures. Just as Kraus declares that there is little result shown in shoeing for proximal structure problems, it should be clear that the addition of shoes will sooner be detrimental – to give him the benefit of the doubt, we could say that any envisaged amelioration will be cancelled out by detriment!
Caulks, trailers, studs –whatever name you might want to use– are always going to turn an already damaging situation into a potential disaster. As stated in the article, the possibility of sticking and 'torquing' –spraining– joints brings some veterinary surgeons and farriers, quite rightly, to argue against their use. The final statement rather clinches it though: '[their use] often depends on the equestrian activity and terrain conditions'. We are talking arthritic horses here. We should be adapting our activities to the condition of the horse, not trying to prop it up to get it through next year's equestrian calendar. This is welfare at its lowest – the needs of the rider always seem to go before the needs of the horse. And to say that all this –actually worthless– treatment is for the horse's welfare, is pulling the wool over everyone's eyes, the rider's included.
Traditionally, farriers have applied pads beneath shoes to provide sole protection and shock absorption. Kraus says that in his experience, polyurethane pads provide limited shock absorption and are better suited simply for sole protection. Leather pads do improve shock absorption but deteriorate over time, he says.
“Some synthetic pads are designed to absorb shock; however, with only 1/8-inch of material on a 1,000-pound (or more) horse, how much shock can really be absorbed?” he says. “A pour-in pad or packing a shoe with synthetic gel may be a better option to achieve shock absorption” for arthritic horses. These materials conform to the sole and frog for a more uniform distribution of shock absorption throughout the hoof.
Anything applied to the bottom of the foot is, first and foremost, detrimental to the locomotion of the horse creating an imbalance in movement and moment, raising the heart-rate above normal –partially due to the severe reduction in the hoof-mechanism– increasing the effort exerted for every step.
As the article states, pads have been applied traditionally to provide shock absorption – except generally, they don't. And in any case, the foot is designed to carry the weight of the horse and, more importantly, to cope with the enormous amounts of kinetic energy generated. It is often argued that the horse is not designed to carry riders, which is true, therefore we must 'protect the hoof' against this extra weight. In reality, a horse weighing 500kg will generate almost the same amount of kinetic energy at 16m/s (full gallop) as a 500kg horse with 70kg of rider and tack at 15m/s. The arthritic horses will not –or should not– often be achieving such speeds therefore we should be able to consider that he is already equipped with all the shock absorption he will ever need. And the first point of shock absorption is the frog. Shoeing the horse removes almost all function of the frog and it is not by any means unusual to find this structure almost completely atrophied in the shod horse.
Considering shoe weight and type
Any type of shoe on a horse’s foot adds weight that the animal must lift from the ground at breakover. To reduce shoe weight, try applying aluminum shoes, which are one-third the weight of steel, says Kraus. “Or, an alternative to bar shoes is the Myron McLane pad that includes frog and heel support,” he says. Wide web shoes are another support option and weigh less than egg bar shoes.
Synthetic shoes—nonmetal or a metal composite with nonmetal materials—absorb the most shock. You can choose from many types of those shoes, both nail-on and glue-on. Remember, however, that plastic materials can be slippery on wet grass or ice and might wear more quickly than steel shoes. “With arthritic horses, it’s a delicate balance between slip and grip,” says Kraus.
'Try aluminium shoes to reduce weight...they are a third of the weight of steel' – but they still increase the distal mass by around 50%. This is still a locomotive impediment. And worse still, the weight of the horse is still being moved out onto the non weight-bearing structures: the hoof wall and the laminae, and the impact concussion is not being absorbed but rather amplified (there are numerous videos on the internet which show exactly how this amplification makes itself visible).
Barefoot or Shod?
“Leaving a horse barefoot is generally good, particularly in a nonperforming horse with arthritis,” says Parks. “In most cases, the unshod hoof capsule provides the best damping to assimilate the shock of foot impact. And, a barefoot horse is able to ‘roll’ its own hooves through natural abrasion.”
“When barefoot arthritic horses wear their hooves to their comfort level, this shouldn’t be confused with conformational defects that often wear the hoof in the opposite direction than the horse needs,” says Kraus. However, “barefoot horses with thin soles may become sore-footed and then alter their gait in such a way to strain arthritic joints.”
Still, barefoot advantages might outweigh disadvantages to help curb arthritic pain, and owners can apply hoof boots for riding or navigating rough terrain, if needed. Our sources recommend using a lightweight boot with built-in breakover and adding a viscoelastic pad inside.
There is no question here – the horse should never be shod, arthritic or not. The idea that the horse will get out of its comfort zone implies that we are doing too much with the horse.
Before making trimming and shoeing changes, have your veterinarian perform a thorough diagnostic work-up of your horse’s lameness problem. Ask him or her take radiographs to visualize the angles of internal hoof structures, the extent of osteoarthritis in a joint, and the depth of sole a farrier has to work with.
“Shoeing methods for arthritic horses ideally incorporate ways to transfer motion to the ground instead of to painful joints,” says Kraus.
“Shoes modified properly to help with arthritic problems may be a more permanent way to manage some horses with arthritis,” says Parks. “Trimming and shoeing practices are useful adjuncts to multitreatment modalities that include joint injections, non-steroidal anti-inflammatories, IRAP (interleukin-1 receptor antagonist protein), and in some cases regenerative therapies.”
There is no single trimming or shoeing recipe that farriers can apply to every horse. Following basic principles of balancing the foot, easing breakover, supporting the heels, and aligning the hoof-pastern axis provide the best foundation for both normal and arthritic horses.
The take-home message is clear. DO NOT SHOE. The article states that '...[there] is no single trimming or shoeing recipe that farriers can apply to every horse...', but there is. It is impossible to correct or compensate for arthritic problems with either shoes or trimming. But we can give the horse the ability to find its own balance, its own correction or compensation:
Make sure your horse is trimmed regularly and correctly. That means NOT how the farrier will generally trim, after all, the farrier knows how to trim to shoe, but not for the functioning of the locomotor apparatus; his training will not have given him insight into this (although subsequent experience may). Heels down, wall short. If your horse is high-heeled or underrun, then any changes must be made gradually – this applies just as much to the fully fit as to the arthritic horse.
Remember that it is his welfare we should be considering. Shoes are never the solution and if your horse cannot do what you ask barefoot, then you are either asking the wrong thing, or you are not thinking of his welfare. Shoes and welfare never mix. Riders and owners often say that they shoe because they are thinking of the horse's welfare and then ask the horse to do those things which are not going to be good for his health...