By Dr. Jennifer Miller-Bailey

 

The dreaded “L” word. No owner wants to hear their horse has been diagnosed with laminitis. Veterinarians dread diagnosing horses with laminitis. For most veterinarians it means sentencing the horse with a life of pain and likely death. That is because for most veterinarians, that is exactly what happens to the horse when the traditional approaches to laminitis are taken.

In veterinary school, very little is taught about the foot, let alone laminitis. We learn that in the purest definition, it is inflammation of the laminae. This inflammation, brought on by many causes, always results in the same process: destruction of the bond between hoof and bone resulting in the alteration of this relationship. We are not taught how to treat laminitis, just as we are not taught how to treat many other ailments of the foot. That is likely because there is no widespread agreement between academic veterinarians, private practice veterinarians, or even farriers on how to treat laminitis or many other conditions of the foot. Because of this, the horse suffers.

There is however, a method for addressing laminitis and the destruction it causes, that in my experience far surpasses any other method available. I was introduced to these methods and concepts five years ago when faced with a very difficult case that had extensive damage throughout many levels of the foot and distal limb of both forelimbs. After several very costly diagnostics and treatment by other veterinarians, this horse was still in a great deal of pain. Yet by addressing the mechanical reasons for the pain, this horse was pasture sound in 6 months and delivered her first foal two years later. This approach opened a whole new world of possibility for lame and laminitic horses that had been previously hidden from me.

I have always gravitated to the foot. Through veterinary school, internship and private practice, it seemed like an obvious place to focus given that 90% of lamenesses are foot based or related. Looking back, it seems astonishing and disappointing that we don’t learn more about the foot in school. I have sought out assistance and teaching from farriers and other veterinarians that focus on the foot over the past several years. This has given me the opportunity to use more traditional approaches to the foot and follow their results. For the last five years however, I have been utilizing a different approach and the results I have been getting are overwhelmingly positive.

The approach I now follow is based on mechanical principles identified and described by Dr. Ric Redden of Versailles, KY. He is a Veterinarian and Farrier that has over 45 years of studying and treating the various pathologies of the foot. The foundation of his approach is centered on addressing two main structural systems of the foot: support components and suspension components. The support components are the hoof capsule, sole, bars, frog, and digital cushion. Suspension components are mainly the deep digital flexor tendon and the lamellae connecting hoof capsule to coffin bone. These two systems are simplistically represented in the image below. The support system is shown in green as coils and shock absorbers. The suspension system is shown in yellow as small springs (laminae between the hoof wall and coffin bone), large spring (deep digital flexor tendon), and pulleys (navicular apparatus). The red arrows show the directional forces at play around the various structures.

 

 

 

 

 

 

 

 

 

I’ve always understood the support system. That is where most farriers and veterinarians focus their attention. Shoes, pads, sole packing, etc. are all designed with support in mind. What I now realize is without addressing the suspension, we are missing the mark by a mile. The two systems are closely linked. One cannot expect success only addressing one of them. In fact, not only can one not expect success, they can expect out right failure when treating laminitis.

 

If we look at the two systems separately in the simplistic drawings below starting with suspension, the two main players are the deep digital flexor tendon (ddft) and the lamellar attachment between hoof wall and coffin bone. The ddft (orange line) is anchored at the elbow, runs down the leg to insert on the bottom/ventral surface of the coffin bone, and exerts a rotational force on the coffin bone via the pulley action of the navicular bone. In a healthy foot this force is equally antagonized by the strong Velcro-like lamellar tissue (purple arrows) that hold the hoof wall to the coffin bone. Therefore, the coffin bone, and thus the digit, is “suspended” within the hoof capsule by these two very robust structures. This can also be illustrated by picturing a hammock; one end anchored by the lamellar tissue, the other end by the deep flexor tendon. A large portion of the horse’s weight is directed down into this “hammock.” The remainder of the horse’s weight is distributed through the support structures.

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If we now examine the support system, the main players are the hoof capsule, sole, frog, digital cushion and the phalanges (long and short pastern bones and the coffin bone). The weight of the horse is directed down through the skeleton into the foot and is represented by the green arrows pointed down through the middle of the phalanges. In a healthy foot, this force is equally opposed by the ground pushing up (as shown by the shorter green arrows pointing up from the bottom of the foot) via the hoof capsule, sole, frog and digital cushion, against the bottom of the coffin bone.

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The support and suspension systems work together to keep the relationship between the bone and the hoof capsule stable throughout all sort of mechanical stresses placed upon the foot during the horse’s performance. In a “normal” appearing foot, meaning one that is not upright or clubby, nor does it have low underslung or crushed heels, these two systems are in perfect harmony. However, if one system is overwhelming or insufficient, the foot takes on either an upright or clubbed appearance (too much suspension), or a low angled underslung or crushed heel with minimal digital cushion (not enough suspension). Genetics can predetermine this arrangement, but environment, nutrition, injury and disease also affect it. Laminitis significantly disturbs the balance between suspension and support.

 

When a horse is experiencing laminitis, no matter the cause, the suspension system is disrupted. The laminar bond between hoof and bone is no longer equal to the pull of the tendon. This results in tearing of the laminar tissue and eventually rotation of the coffin bone. If enough lamellar tissue is disrupted throughout the foot, the entire bond can fail resulting in sinking of the coffin/digit further down into the hoof capsule. If support alone were enough to prevent this from happening, horses would never penetrate the sole with their coffin bone. However, all the support in the world will not prevent this from happening if that is the only system addressed.

 

When treating laminitis, one must always address both systems to have success in either preventing rotation or preventing further vascular damage and bone loss after rotation has already occurred. There is a vast and delicate vascular network tightly associated with the coffin bone, especially around the distal rim or apex where the circumflex artery lives. As the tendon pulls on the coffin bone, the apex is pulled down against the sole and away from its vascular supply, the circumflex artery. The bone not only begins to suffer damage from loss of perfusion, it compresses additional vasculature below it within the solar tissue. This compression prevents perfusion of the sole, leading to tissue death and necrosis. If this continues long enough, there will be irreversible bone loss and minimal to no sole growth in this area. The solar tissue becomes very thin and fragile and the bone begins to penetrate the sole.

 

The pictures below show a venogram. Dye has been injected into the digital vein and a radiograph produced to show the intricate and vast network of vessels throughout the foot. Venograms produce real-time information on the vascular status of a foot with laminitis weeks before radiographs would show any evidence of laminitis. They allow diagnosis and intervention to be implemented before irreversible damage has occurred. Serial venograms can be utilized to evaluate the effectiveness of the interventional treatment to be sure it is adequate to save the foot. In the event interventional treatment is still insufficient, more aggressive tactics can be taken before it’s too late. Venograms are now the gold standard in diagnosing and evaluating laminitis. The first picture shows the vascular pattern without any intervention. The second picture shows how that pattern is changed when mechanics are introduced. Notice there is relative blanching of the vessels throughout the heel region, and relative filling of vessels through the coronary waterfall, sublamellar vascular bed and circumflex artery. This is proof that application of mechanics alters the bloodflow in the foot to allow. Taking advantage of this effect allows us to protect and or rehabilitate damaged areas.

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Once the diagnosis of laminitis has been made, immediate mechanical intervention should be implemented to address both the support and suspension systems to prevent any further damage from occurring and promote vascular and tissue repair at the fastest rate possible. The pull of the tendon must be significantly reduced to prevent the coffin bone from moving, and the load must be directed towards the healthier heel area and away from the toe where most of the damage is occurring. Over the past 45 plus years Dr. Ric Redden has found that in most cases of laminitis, reducing the pull of the tendon by 60% is sufficient to prevent further catastrophic damage. He has found that raising the angle of the coffin bone relative to the ground to around 20-30 degrees will achieve 60% reduction in the ddft tension. Dr. Redden also discovered that by loading the heel parallel to the coffin bone, one can maximize the amount of perfusion around the toe. This effect can be illustrated by simply applying digital pressure to your skin. The blood where the pressure is applied is pushed into other surrounding tissues. By applying increased pressure at the heel, we can move more blood into the toe, thus reducing or preventing tissue necrosis due to inadequate perfusion.

 

The picture below is a device used to treat the very early stages of laminitis utilizing the above described principles. It was designed to be applied as a first aid type of treatment, before any rotation has occurred. Applied correctly with the aid of radiographs, it can be a very effective method of treatment. Combined with serial venograms, the possibility of getting a horse to not only survive laminitis, but to have a normal foot afterwards is quite possible with this treatment. As mentioned before, this device can provide a 60% reduction in the tension of the ddft. If, however serial venograms show that the degree of laminitis has overwhelmed the ability for this device to save the foot, more aggressive measures can still be taken to save the horse and save the foot without having the catastrophic damage and distortion we have become so accustomed to associating with laminitis. In the event diagnosis is delayed and rotation does occur, mechanical intervention can still save the foot so long as the venogram shows the vascular supply is still present.

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The results produced when utilizing and applying the principles of this mechanical formula have far surpassed any other method I have used or seen to date. Why it has not yet become the standard of care for laminitis is due in large part to the concept being so different than the traditional “American Farriers’ Association” style of teaching. Principles of the AFA are largely what govern the approaches of most veterinarians and farriers. I have utilized those principles for years. I have now realized that those principles are largely inadequate. Following the mechanical principles above has allowed myself and many others to help substantially more horses than I ever was able to with more traditional approaches. In addition, the degree of success for each horse has been far greater.

 

Successful implementation of mechanical treatment for laminitis must be done by likeminded individuals. The veterinarian and the farrier must be on the same page and have the same goals and ability. Laminitis treatment can be intensive and ongoing for months to years in some cases. This requires dedication from the veterinarian and the farrier that is unlike most other diseases of the foot. It also requires that the veterinarian and the farrier work together on the horse at the same time to compliment one another’s efforts. This level of commitment is likely why many veterinarians prefer not to treat many laminitic horses and would rather turn them over to the farrier exclusively. In these situations, the owner and or farrier often seek out a veterinarian whose practice does focus on laminitic horses. Many times, however this occurs weeks after initial diagnosis making treatment more difficult and prognosis lower. Prognosis and outcome are maximized when the appropriate treatment is applied at the first sign of laminitis. An experienced vet-farrier team can immediately work to get the horse healthy again and provide the owner with the best possible outcome in the shortest time frame possible. Therefore, I have made it my goal to educate horse owners on the importance of not only recognizing the early signs of laminitis, but the importance of getting the right team for the job. If you or someone you know has a horse suffering from laminitis, put them in touch with professionals such as myself that are trained in this method and have experience using it. It can mean the difference between life and death for many horses.