Laminitis: Coming Out of the Dark (Bluegrass Laminitis Symposium)
Some people make it their life's work to study and shed light on some poorly understood aspect of equine veterinary medicine. Their trailblazing work changes the way we evaluate and understand that problem, and it provides the information we need to improve how we care for horses in today's world.
Italian equine podiatry veterinarian Lorenzo D'Arpe, DVM, of the University of Padua's Department of Clinical Sciences, is one such pioneer, and his chosen field is equine laminitis. At the recent Bluegrass Laminitis Symposium, held Jan. 25-28 in Louisville, Ky., he discussed some of his cases and research. Additionally, The Horse caught up with him to discuss his history and theories of laminitis with this so-called "Mission Impossible veterinarian."
One could hardly call D'Arpe's perspective limited, after his study at the University of Bologna in Italy; the University of Illinois, guest tour at Rood and Riddle Equine Hospital in Lexington, Ky.; PhD work at the University of Padua; and continuing study with Ric Redden, DVM, founder of the International Equine Podiatry Center in Versailles, Ky.
"Coming to the New World from the culture of the oldest university in the world has completely changed my life," he says. "It has been a real adventure."
His focus on the equine foot and laminitis began with an invitation from Redden to work with him at the International Equine Podiatry Center (IEPC) about five years ago. Since then, D'Arpe has spent time in Kentucky at the IEPC, back home in Italy to trim and shoe with the "foot encyclopedia" farrier Hans Castelijns, and around the world assisting Redden on laminitis cases.
"When I first arrived at his place, I asked Doc, 'Why do you want me to work with you when, compared to the information I have collected so far, you are outside the world with your knowledge of laminitis? I know nothing about the foot,' " recalls D'Arpe. "He said, 'You see, that's why. It is so much easier to fill an empty glass than to empty it and fill it again.'
"Now I'm his European assistant," he says with a laugh. "Having me there reduces the economical gap between European horses and Doc's knowledge. He has differentiated himself with results. What has happened (since working with Redden) is I get more and more cases of high-scale laminitis, so I have become a little bit like the Mission Impossible veterinarian. But that is okay, because I really like to do something that can be very significant for horses' lives."
In addition to working on severe laminitis cases, D'Arpe's efforts focus on two more areas:
- Spreading knowledge of this frustrating disease, and
- Researching the biomechanics of the horse's foot to learn how to treat it more effectively.
"Teaching people about laminitis is like this big wheel that is very hard to push at the beginning, then it gets momentum and it gets easier," D'Arpe commented. "Communicating this information is very exciting and it's making me learn different languages. I speak Italian, Bolognese dialect, British English, American English, French, and Spanish. I am willing to learn German, maybe Chinese, Japanese, whatever is needed.
"All the foot people, they think in two dimensions, and what happens inside the IEPC is thinking in three dimensions," he says. "When I see feet, I am thinking about pyramids, spheres, and cubes, and most people think about triangles, circles, and squares like in E. A. Abbott's book Flatland. If you want to deal with laminitis or many other foot pathologies, you need to go to the third dimension. Then it's so much easier to deal with them, because the biomechanics of the horse work in three dimensions, not two."
Thinking in three dimensions isn't the whole answer, however. There isn't yet a complete answer to how laminitis works and how to treat it, although researchers in several countries are working on it. D'Arpe characterizes the current state of laminitis knowledge by comparing it to the early stages of fracture evaluation and treatment.
Radiographs for fractures The veterinary community has come a long way in developing methods for successful repairs of many types of fractures in horses. D'Arpe explained, "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.
"After X ray machines came along, we started to clinically evaluate fractures," he continued. "Now we are going deeper and deeper, we are doing thinner and thinner slices with MRI, and with scintigraphy we can see if a fracture is active (healing) or not. So today when we deal with a fracture, we clinically evaluate the horse and we make a decision on all the hundreds of 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."
Venograms for laminitis "With laminitis, it is just the same thing!" he goes on. "So far, radiography and all the other instruments we have used in trying to find a key to understand laminitis have not been effective. They have helped us to understand maybe 5% of this devastating 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 states. A venogram is a radiograph or X ray taken of the foot after contrast media has been injected, 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. And 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 continues. "You can then make all the therapeutic decisions you need to fix that horse. You are not giving false hopes to your client and you are not telling him incredible things, you are just telling him if he has got a little, medium, or big problem. And you can offer him many therapeutic options, and you can tell him how much time and how much money it will cost him. Then the client can make the best decision he can for his horse.
"Without the venogram, you are driving in the dark," he states emphatically. "It is impossible for any of us to clinically evaluate the horse without it. Venograms are to laminitis what radiographs are to fractures.
"Today, there are probably not more than 60 vets who are able to perform a venogram all over the world, but we are less scared about laminitis," he adds. "And it is one thing to perform a venogram, and totally different to be able to interpret the venogram. I think today in the world, there are three of us who can really read them. Doc told me that to get comfortable with the technique, I needed to perform at least 50, but to be ready to interpret it I needed 500. By the way, before Doc let me do my first venogram by myself, he obliged me to study 3,000 of his cases collected in the IEPC.
"So today, we are pushing a big wheel, an immense wheel, to carry the podiatry world into the third dimension and to correctly use podiatry/radiography techniques and the venogram as the real key (and so far the only key) to understand, prevent, diagnose, and clinically evaluate laminitis, and to treat and find efficient therapeutic options," he sums up. Dï¿½Arpe said he hopes that in 20 years, all practitioners and farriers will be able to encounter laminitis cases with more confidence and less fear.
Learning About Hoof Biomechanics
"There are many scientific groups working hard to put light on the mechanisms of laminitis," D'Arpe says. "And they are doing immense work, but we need biomechanical solutions to be effective, or we still are in the dark."
Center of pressure The biomechanics of the foot are far from completely figured out, but D'Arpe offers a few clues. During the Symposium, he described a technique developed by French farrier Denis Leveillard for finding the static center of pressure (center balance point) of a horse's foot (by placing a plate and strong magnet with a curved surface on the bottom of a horse's foot, then with the horse standing on this magnet, moving it with a thin hammer until the foot is balanced).
"I find this very exciting, because there are many scientific articles about the center of foot mass, but none of them are really able to show where it is exactly without doubt," says D'Arpe. "So now even if you know nothing about the foot, you can see it standing balanced on that dot and follow us in understanding what is happening in that foot."
Starting with this technique, he began finding the center of pressure of a foot when the horse is standing on all four feet, as well as its position when the horse is standing on three feet (with one forelimb raised, as when a laminitic horse shifts his weight between his front feet), to see how it changes with that change in weight bearing. He has also drawn lines of balance between these two points to further understand hoof balance planes.
What's the point of all this? Knowing a hoof's centers and lines of balance helps one tailor trimming and shoeing to achieve proper loading and healing of the feet.
Palmar angles and blood flow "Then one morning I had the idea of building a mechanical podoblock to carry out this center of pressure study to go to the third dimension, so Moreau X. and Orlandi A. helped me to realize it after a year's study and four prototypes," he says. "The podoblock now 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.
"This has allowed me to scientifically prove that palmar angle changes induce vascular (blood flow) changes, and you can visualize this on venograms," he reports. "This has really helped me to understand the biological 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."
His procedure involves standing the horse with one front foot on the block at a 15° angle (the other one was held up) and performing a venogram, then tilting the block back and taking a venogram image every 5° (every 30 seconds to allow blood vessels to adapt to the angle change) until he reached -15°. The reverse procedure was also done a week later.
"You can see differences on the venogram that Charlie Chaplin can appreciate, without knowing anything about veterinary medicine or podiatry," he says. "I was aiming to demonstrate that changing the palmar angle modifies the vascularization (blood supply) of the foot. That's the relationship between palmar angle and venograms. In other precedent articles on this concept, I compared different horses at different times. With this experience, I have related palmar angle to venogram changes on the same horse at the same time. The biomechanics of the foot can influence its vascularization; this is a good key to understand laminitis."
The value of this kind of work is that 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.
"The most exciting thing about this is that the results are repeatable," he adds. "That's the first step for any experience to be a scientific process. And so I have collected all these data, now I am elaborating them statistically and scientifically with Prof. Bernardini D. and Dr. Coppola L., to present this to the World Equine Veterinary Association meeting in Moscow (in January/February 2008). I have been invited to this meeting by E. Zabegina, the president of the Russian Equine Veterinary Association."
"I completely understand why clients, colleagues, and farriers are scared about laminitis," he concludes. "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). I can see trees and other problems, and find options to get around them."
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: University Equine Hospitals