The Quest to Conquer Laminitis
"Success today with laminitis is the result of the dedicated efforts of veterinarians and farriers who take it upon themselves to learn how to evaluate and treat the various stages of this complex disease," he said. "My teaching on podiatry and laminitis is not a reflection of what veterinarians and farriers should know or should have learned, but my means of sharing my life's work in hopes of putting a little light at the end of the tunnel for those who share in my enthusiasm and desire to conquer this clinical disease."
Redden and his family host the Symposium almost yearly in pursuit of that goal--conquering laminitis. Selected additional podiatry topics are provided as well. Following are excerpts of the presentations given during this year's Symposium, along with links to more information on each one at www.TheHorse.com.
Laminitis: Coming Out of the Dark
Italian equine podiatry veterinarian Lorenzo D'Arpe, DVM, of the University of Padua's Department of Clinical Sciences, presented some of his cases and research during the Symposium. Additionally, The Horse caught up with him to discuss his theories on laminitis.
D'Arpe characterizes the current state of laminitis knowledge by comparing it to the early stages of fracture evaluation and treatment. The veterinary community has come a long way in developing methods for successful repairs of many types of fractures in horses. "If we think about fractures some decades ago before X rays, vets and farriers were taking care of fractured horses with no hope, and everybody in the world knows that in that period, a fracture corresponded to euthanasia of the horse," he explained. "Today when we deal with a fracture, we clinically evaluate the horse and use X rays, and we make a decision on ... therapeutic options. It's easy today, we can tell the owner how many days or months or years it will take to fix the horse, and if it is easy, medium, hard, or impossible.
"So far (with laminitis), radiography (X rays) and all the other instruments we have used in trying to find a key to understand laminitis have not been effective," D'Arpe said. He added that these methods have helped the veterinary profession understand only a fraction of what there is to know about this disease. "But everybody's still in the dark."
"The venogram is really the key to understanding laminitis, because with the venogram, you can really see the dynamic in static biomechanical effects of what the horse's weight and gravity force is doing in that moment to that foot's vascular bed," D'Arpe stated. A venogram is an X ray of the foot after contrast media has been injected into the foot's blood supply, so you can see if there is any compromise of vascular architecture. If an area has no blood flow, it will not receive the nutrients it needs to heal unless the biomechanics of the foot are changed to encourage blood flow to the area. If part or all of the foot continues to have no blood flow, the tissues will die, and the horse will often be put down.
"So the venogram has immense diagnostic value," he continued, and you can follow up by making therapeutic decisions to help that horse. "Without the venogram, you are driving in the dark. It is impossible for any of us to clinically evaluate the horse without it. Venograms are to laminitis what radiographs are to fractures."
Venogram research D'Arpe discussed his investigation of the effect of foot angles on blood flow within the foot using a podoblock he developed with farriers. "The podoblock allows me to stand a horse's front foot on it and change the foot angle in a controlled manner, then take venograms to evaluate the changes in blood flow with the changes in hoof angle," he explained (see diagram above).
"This has allowed me to scientifically prove that palmar angle changes (alterations in the angle between the bottom of the coffin bone and the ground) induce vascular (blood flow) changes, and you can visualize this on venograms," he reported. "This has really helped me to understand the biological (and biomechanical) mechanisms of weight and weight force compensated by the bone angles and tendons' tension, so that I can know how to improve the vascular bed of the foot."
Knowing how hoof and bone angles affect blood flow can help veterinarians and farriers understand how to modify trimming and shoeing practices to direct blood flow toward areas that are compromised and need healing.
"I would be scared to drive a car without lights at night, unable to see trees. But I am not scared about driving with lights (or working with laminitic horses using venograms and knowledge of biomechanics to light the way)," D'Arpe concluded. "I can see trees and other problems, and find options to get around them."
For more information see www.TheHorse.com/ViewArticle.aspx?ID=9241.
Learning to Read Radiographs
Reading radiographs takes a trained eye, and it's an important part of evaluating the horse's foot, especially when lameness exists. But number one on Redden's list of important points about interpreting radiographs was that they aren't the be-all and end-all of diagnosing foot problems. They are but one part of the entire examination of that horse, which includes physical examination, gait analysis, and possibly other diagnostic procedures. As much as we might like a nice checklist of things to do for lameness examination, he says it isn't that easy.
"Everybody wants a standard, but that's the easy way out," he began. "We don't need a standard, (but rather) we need a standard way of thinking. When you make this evaluation a careful, systematic thinking and observation process, you'll see a lot of things you might otherwise miss.
"Over the many years I have worked as an equine podiatrist, I have come to appreciate the fact that soft tissue pathology is present to some degree in every footsore horse," Redden stated. "Thus, evaluation of the soft tissue zones within the hoof capsule is an extremely important part of radiographic examination of the foot."
He measures the following characteristics of each foot on a radiograph (see diagram below left):
- Sole depth (SD) is the distance between the bottom of the tip of the coffin bone and the sole surface (pink lines).
- Palmar angle (PA) The green lines show the angle the bottom of the third phalanx makes with the ground surface of the hoof.
- Digital breakover (DB) is the distance along the ground from the tip of the third phalanx bone to the forwardmost point of contact between the shoe and the ground (purple).
- Horn-lamellar zone (HL) is the space between the face of the coffin bone and the outside of the hoof wall (orange).
- Coronary band-extensor process distance (CE) is the distance between the top of the extensor process of the coffin bone and the top of the wall at the coronary band (blue).
He concludes, "There are no shortcuts to examining the foot. You have to methodically learn everything you can about that foot and that horse in order to understand what's going on, what you should do to help it heal, and why your solution will work."
For more information see www.TheHorse.com/ViewArticle.aspx?ID=1457.
Venograms: The Difference Between Success and Failure
Success when treating laminitic horses depends on several factors, but an accurate knowledge of the extent of the damage within the feet and a plan for treating it is paramount. Redden also discussed using venograms to increase the success of laminitis treatment by increasing his knowledge of the damage present.
"When dealing with an acute laminitis case, I perform a venogram on the very first (initial) examination, because I need that baseline to see what condition the foot is in," Redden states. "Especially in the acute case, you want to know what degree of vascular compromise is present. The initial venogram is extremely valuable, as it may indicate only minor vascular compromise in a horse that is glued to the floor (not wanting to move because of the pain), or it can reveal stark loss of contrast (lack of blood flow) throughout the majority of the hoof with a horse that appears to be only slightly lame. Either of these horses presents a very deceptive clinical picture."
He described to his audience the typical measurements and characteristics of healthy feet as seen on venograms, as well as the typical unhealthy findings in crushed feet, club feet, supporting limb laminitis, and acute and chronic laminitis.
"Horses are very durable, and they'll lie through their teeth about how they're feeling," Redden said. "Do not depend on the horse to tell you how healthy the laminae are. Depend on your venogram."
For more information see www.TheHorse.com/ViewArticle.aspx?ID=9244.
How to Use Venograms to Evaluate Laminitis
"The venogram is the ticket to fixing all those laminitis cases you've been missing," said Amy Rucker, DVM, of Midwest Equine in Columbia, Mo. She discussed how to use the venogram in clinical situations.
She began by listing the phases of laminitis: developmental, acute and subacute (some mechanical collapse), and chronic. "Each phase has different degrees of damage, and they can bounce between the chronic and acute stages (chronic with flare-ups)," she said. The results of a venogram help her determine which phase a horse is in, she noted.
Once the horse has been evaluated, it's time to plan treatment. "Laminitis is a medical emergency, and should be treated as such," Rucker stated. "Waiting to see how the horse does over time (without treatment) only decreases your chances of having a functional horse. The basis of treatment of the laminitic horse relies on correcting the initiating disease process, managing the horse's pain, and altering the mechanics of the hoof to place it in a healing mode.
"For the foot to repair, the laminae and dermis cannot be damaged beyond repair, and the foot must have an adequate blood supply throughout," she went on. "The venogram shows where blood is in the foot; if the foot is unstable, that will affect the blood supply within it. The amount and patterns of displacement of the contrast media suggest where the foot is heavily loaded, where architecture has collapsed, and/or areas of vascular impairment."
Knowing where vascular damage has occurred provides the information needed to tailor shoeing treatment to support these areas and help them heal.
"Also, serial venograms allow assessment of progress in a case, or lack thereof," she added. "Always trust the venogram before the clinical picture. Clinically they can look really good even with a very bad venogram (and when this occurs, the horse that looks fairly sound will later crash due to the compromise of blood flow in his feet)."
For more information see www.TheHorse.com/ViewArticle.aspx?ID=9245.
Rucker discussed ways to improve communications among the various members of the team caring for a horse, including the farrier, veterinarian, owner, and possibly a trainer and/or an insurance agent.
"How do we communicate?" she asked. "We exchange ideas. It isn't me talking and you having to listen to it all. The veterinarian, client, farrier, and trainer (if applicable) all need to be together to discuss the plan of action for this horse. There needs to be clear communication about all aspects of a case.
"Veterinarians and farriers often have different ideas, backgrounds, and vocabularies," she said. "But we have to communicate, and I think our language is going to be numbers. What numbers do we have (measurements of various foot parameters)? What numbers are we looking for? What numbers determine success, and which ones mean failure? I really think numbers are what are going to unify the vet and farrier.
"Record what's going on and set goals and expectations," she advised. "For example, I might say that if this horse hasn't grown 3 mm of sole in a certain period of time, we're going to do another venogram to see how his blood flow is doing, etc. We need benchmarks."
For more information see www.TheHorse.com/ViewArticle.aspx?ID=9246.
What We Know About Laminitis
Theories about the causes and cures of laminitis abound in the horse industry, in large part because research hasn't yet been able to give us solid, unassailable explanations for much of the disease's processes and treatment. But there are some concepts that we do know, for sure, about laminitis. Rustin Moore, DVM, PhD, Dipl. ACVS, professor and chair of the Department of Veterinary Clinical Sciences at The Ohio State University, reviewed research on several aspects of laminitis.
He began, "A complete knowledge and understanding of laminitis and its complex pathophysiologic cascade remains elusive, despite substantial efforts by many scientists and clinicians over the last few decades, and thus preventive and therapeutic management strategies remain empirical and anecdotal with little emphasis on evidence-based medicine."
He noted that there are at least five theories of how laminitis initially damages the hoof's laminae, ultimately resulting in changes to the foot's structure and microanatomy, weakening of the laminae, rotation/sinking of the coffin bone, and clinical signs of laminitis. These include the vascular or ischemic theory, enzymatic/toxic theory, inflammatory theory, metabolic/endocrine theory, and biomechanical theory. He discussed the rationale and research (or lack thereof) on the various theories. In fact, all or many of these pathways are likely involved in the complex pathophysiologic cascade.
Lastly, he described several treatment options for laminitis and research on their use. Cryotherapy (cold therapy), heat therapy, loading variation, vasodilatory drugs (that increase blood flow in the foot), anti-inflammatory medications, and diet/weight management were discussed.
While there is some value to these treatment approaches in specific situations, "A more complete understanding of the pathophysiology of laminitis is needed to develop more effective preventive and therapeutic strategies," Moore concluded.
For more information see www.TheHorse.com/ViewArticle.aspx?ID=9247.
What Is a Healthy Hoof?
Ask 10 people what a healthy hoof should look like, and you'll likely get 10 different answers. And those answers will likely include general statements like "proper toe angle," "enough heel," or "plenty of foot mass." But what exactly do these descriptions mean?
Richard Mansmann, VMD, PhD, clinical professor and director of the North Carolina State University College of Veterinary Medicine's Equine Podiatry and Rehabiliation Service, presented the results of several research projects that tried to answer the question: What are the characteristics of a healthy horse's hoof?
Mansmann has long recommended that horses' front feet be radiographed annually--that includes sound horses as well as lame ones. "My goal with this is to look at it from the perspective of prevention rather than treatment," he said. He'll take measurements and compare them against the horse's previous measurements to identify any significant changes that can lead to problems.
These annual radiographs, along with horses' work histories, have provided him with a great deal of information on sound feet. He used them to discuss the value of several generally accepted characteristics of "good" feet and how closely sound horses' feet matched them.
"As veterinarians and farriers, we all need to educate owners about the value of proper foot conformation and the consequences of bad conformation," he concluded. "We have to look at the horse and his feet. When his measurements change over time, that is very good information to know. And having an unhealthy-looking foot can even end up as a life-threatening situation. It is a disease in itself."
For more information see www.TheHorse.com/ViewArticle.aspx?ID=9248.
Laminitis Lessons: What Not to Do
"Any of us dealing with laminitis have our successes, but we've also had our share of failures," said Bill Baker, DVM, of Equine Associates in Hawkinsville, Ga. "These failures are usually the most memorable, but least-discussed cases. This is unfortunate, because we can all learn from failures--those lessons are where successes are born. Hopefully you will learn from my mistakes and ignorance so you will not have to repeat them."
Baker, who is a veterinarian as well as a farrier, presented a discussion of six case studies and what they taught him not to do when treating horses with laminitis. He described the following common causes of treatment failure.
- No plan.
- Available skill The case exceeds the skill level currently available (of the veterinarian, farrier, and/or owner).
- Finances "I don't care how many people tell you money is no object, it is an object," Baker said.
- Lack of owner compliance with care/ aftercare "When I see the horse back for a reset and we're back to the beginning, and the owner says, 'He was fine when I rode him yesterday'--against my instructions--that just overturned the whole boat," he said.
- Owner influence during treatment "My rule is that owners are the financial backers and ultimate decision makers, but I don't want them getting under the horse and trying to help me out," he said.
- Too many chiefs and not enough Indians "If you don't have someone in charge to make the plan, and people around to work the plan, you set yourself up for failure," he commented.
- Poor communication with client and farrier "Be forthright and honest with yourself and your client," he recommended. "Speak in common language, not veterinary terminology--be understood!"
For more information see www.TheHorse.com/ViewArticle.aspx?ID=9249.
Self-Adjusting Palmar Angles for Healing Hooves
Redden also discussed massaging hoof circulation (thereby stimulating healing and hoof growth) with self-adjusting palmar angles. His approach is simple--he applies shoes with curved ground surfaces (termed banana shoes, rock and roll shoes, or full-motion rocker shoes) that let the horse stand with his feet at whatever angle is most comfortable. This will be the angle that relieves the most pressure on damaged areas, allowing them to rest and heal.
Additionally, the nature of the curved shoe means the horse's hoof and bone angles will change as he shifts his weight, even if his feet never leave the ground. As the horse's weight and his anatomy shift, the blood supply within the foot is continually altered and massaged.
"The ability to adjust the palmar angle while in the static state (standing still) sets the mechanical advantage of this shoe well above those that do not influence the static palmar angle," he explained.
He noted that these shoes can help horses with thin soles and walls, underrun heels, white line disease, chronic laminitis, and full-thickness toe cracks.
"This shoe concept has been very beneficial for cases that have problems associated with less-than-optimum foot mass, as it consistently accelerates sole and horn growth, enhancing the protective function of the hoof capsule," Redden concluded.
For more information see www.TheHorse.com/ViewArticle.aspx?ID=9250.
Fighting White Line Disease
White line disease might not be a big deal initially, but left untreated, it can undermine large amounts of your horse's foot (or feet), resulting in lameness and instability of the coffin bone within the horse's foot.
"White line disease doesn't seem to occur without some sort of mechanical stress (such as long toes or hoof damage from previous disease or injury)," Baker began. Opportunistic bacteria and/or fungi then invade the defect and begin destroying hoof wall from the inside, starting at the bottom and working their way up.
"There is no breed, age, or sex predisposition to this disease," he noted. "It occurs in anything from Minis to drafts, donkeys, and mules. It may invade one foot or all four feet."
He said the disease initially causes no lameness at all, and typically a farrier will see this during routine trimming--long before a veterinarian will be called. If a veterinarian is called, he/she can X ray the feet to see how far up the hoof wall the separation has progressed.
Baker summarized this disease and its treatment with the following comments:
- There is no clear pathogenesis for white line disease, but there has to be some mechanical stress in the hoof wall for this to occur.
- The best treatment starts with support of the foot. Do not resect (cut away parts of the hoof wall) without a plan for support!
- Exposure appears to be the best treatment. Apparently whatever's causing this likes a low-oxygen environment.
- No medicines on the market have been proven effective.
- Research is much needed for this disease.
- Treatment is effective, if early and aggressive.
For more information see www.TheHorse.com/ViewArticle.aspx?ID=9253.
Correcting Crushed Heels
"We see a lot of chronically lame horses trying to work with long-toe, low-heel conformation," Mansmann began. "The lower the hoof angle, the more stress is placed on the posterior part of the hoof and limb (ideal hoof angles range around 54° in front feet and 58° behind, he noted).
"These horses have a serious, chronic problem that will take long-term, conscientious monitoring and treatment to maximize soundness," he stated. "The longer the problem has existed, the greater the overall damage to internal and external structures. If the problem is fairly new, you might be able to return to normal (healthy) foot conformation, but you may not be able to reestablish decent posterior digital cushion very quickly."
Mansmann discussed seven types of low heels and how to avoid and correct them. Heel wedges are commonly used to raise low heels, but he warned that they can crush the heels further when used on front feet. The goal is to get the heels growing more, which means redistributing some of the crushing forces elsewhere in the foot so the heels can heal. He notes that moving breakover back can be helpful, as this makes it easier for the horse to lift his heels off the ground when moving. He also noted that consistent lateral radiographs to assess the internal structures and progress of the work are essential.
"Treating low heels is always a work in progress," advised Mansmann. "We can improve horn quality of the heels and hoof mass, and we can generally improve sole thickness 2-4 mm per shoeing to a total of 15-25 mm. By mechanically making the hoof-pastern axis normal, we make many horses sounder."
For more information see www.TheHorse.com/ViewArticle.aspx?ID=9254.
Treatments for Foal Deformities
Angular and flexural limb deformities in foals are concerns, but they're not necessarily kisses of death. Redden discussed treatments for these deformities, both surgical and nonsurgical.
"It sounds simple enough to say a foal toes in or out, but it is actually much more complex than that," he said. "We need to be able to recognize the deformity, classify it to some degree, have knowledge of growth plate closure, and be alert to the stress that corrective aids can put on the rest of the limb and foot."
He described his procedures for watching a foal to identify the nature and degree of deformity, as well as treatments for angular, rotational, spiral, axial, and flexural deformities. Often multiple problems are found on the same leg, he noted.
For more information see www.TheHorse.com/ViewArticle.aspx?ID=9251.
About the Author
Christy West has a BS in Equine Science from the University of Kentucky, and an MS in Agricultural Journalism from the University of Wisconsin-Madison.
POLL: Radiographs for Hoof Care