The Quest to Conquer Laminitis
“Owners and trainers worldwide have the feeling that every veterinarian and every farrier have years of experience and vast knowledge about laminitis and podiatry (foot care). Unfortunately, this is not the case,” said Ric Redden, DVM, founder of the International Equine Podiatry Center in Versailles, Ky., and host of the Bluegrass Laminitis Symposium, held Jan. 25-28 in Louisville, Ky.
“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.”
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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)
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