NEWSLETTER. Trimming for Soundness: The Science between the Ground and the Horse. Nathalie L. Trottier, Department of Animal Science, MSU

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1 NEWSLETTER MICHIGAN STATE U N I V E R S I T Y EXTENSION Summer 2008 Volume 13, No. 3 Supported by the Animal Initiative Coalition Trimming for Soundness: The Science between the Ground and the Horse Nathalie L. Trottier, Department of Animal Science, MSU T R Ou ese tlo arc ok h he hoof forms the interface between the horse and the ground. Its functions include providing the body with information about the type of surface the horse is moving over, dissipating concussion following impact of the hoof with the ground and transmitting propulsive forces as the muscles contract to drive the horse forward. Hoof care should enhance these functions while preserving the health and functionality of the hoof. Unfortunately, in many equestrian sports, farriery methods are driven by competitive objectives, with trainers choosing to trim and shoe their horses in a manner deemed to improve movement and performance, sometimes at the expense of soundness. Increased impact shock and/or reduced hoof expansion and blood flow may occur. In recent years, many horsemen have moved away from using farriery to alter performance and instead focused more on trimming methods that promote the health of the hoof and the soundness of the horse. Dr. Bob Bowker, professor of veterinary anatomy, and Dr. Hilary Clayton, Mary Anne McPhail dressage chair in equine sports medicine at the Michigan State University College of Veterinary Medicine, with the assistance of farrier Carl Roghan, have begun studying the impact of hoof trimming methods on hoof structure, health and mechanics. Angle of wall Central groove of frog Bar of wall Collateral groove of frog Sole White line Figure 1. External structures of the equine foot. Inside Trimming Method: The Physiological Trim Wall page Trimming for Soundness The underlying principle of the physiological trim is that it emphasizes weight bearing on the palmar (back) part of the foot and distribution of weight over the heels, bars and frog (see Figure 1), resulting in reduced weight bearing on the hoof wall. This is accomplished by gradual lowering of the heels and beveling of the toe. Hoary Alyssum in Pastures Horses with Back Pain The Facts about 4-H Letter from the Editor Calendar Equine Forage Management Series (continued on page 2)

2 MSUE Equine Program Newsletter 2 (Trimming for Soundness, continued from page 1) Why lower the heels? The heels have to be lowered for the frog to contact the ground. The wall is trimmed to allow the frog, bars and sole to participate in weight bearing. Ground contact will stimulate adaptive changes in the frog and bars, as well as in the internal structures of the hoof that are responsible for absorbing impact shock and supporting the coffin bone. These structures include the underlying digital cushion, lateral cartilages and blood vessels. Contact of the frog with the ground plays an important role in proprioception (awareness of body position) and in stimulating blood flow within the hoof. What s up about that frog? The frog is composed of a flexible, rubbery type of horn with special sensory cells called proprioceptors located in the heel region. Proprioceptors provide information to the central nervous system in this case, the spinal cord regarding the nature of the footing so that appropriate adjustment of posture and movement can be relayed back to the leg muscles to adjust each stride. Thus, muscular activity may be tuned to the hardness of the surface the horse moves on. This is particularly important when the nature of the footing changes from stride to stride. In contrast, the hoof wall is not suitable for transmitting this type of information because of its rigidity and insensitive nature. Stimulation of the proprioceptors depends upon frog and heels contacting the ground. Bottom line: the frog needs to contact the ground so that the proprioceptors can do their job. Stimulation of blood flow. Much of the concussive force associated with hoof contact with the ground should be dissipated within the hoof before it reaches the bones and joints higher up the limb. When the foot is placed on the ground, contact of the frog and bars with the ground promotes the outward rotation of the lateral cartilages (see Figure 2). The outward rotation of the lateral cartilage is crucial to stretch the digital cushion and reduce its internal pressure. The pressure reduction inside the digital cushion creates a vacuum that draws blood through the capillaries in the lateral cartilages and promotes blood flow (see Figure 3). The movement of these structures in the hoof acts as a pump and as an important contributor to shock absorption. The digital cushion, which supports the back of the coffin bone, is composed of fibrocartilage, which is elastic and thus acts as a good shock absorber. Why bevel the toe? Breakover occurs at the end of the stance phase when the heels leave the ground and rotate around the toe. Tension in the deep digital flexor tendon, which runs behind the navicular bone before attaching to the coffin bone, causes flexion of the coffin joint and raises the heels from the ground at the end of the stance phase. Just before breakover begins, tension is high in the distal check (accessory) ligament and the deep digital flexor tendon, putting stress on the navicular region (see Figure 4). In the physiological trim, the toe is beveled from the medial quarter to the lateral quarter to facilitate breakover and reduce forces in the navicular region Figure 2. Photo (left) and illustration (right) depict the location of the lateral cartilages (LC) on medial and lateral sides of the heel. The cartilages extend above the coronet from their attachment to the coffin bone. Arrows are meant to indicate outward rotation of the LC when the frog and bars contact the ground.

3 3 MSUE Equine Program Newsletter (Trimming for Soundness, continued from page 2) Figure 3. Illustration (left) and photo (right) depicting the location of the digital cushion (DC) relative to the internal structures of the foot. and the tendinous structures. The angle of the bevel depends on how far it extends back on the solar surface and how far it extends up the outer wall. The outer edge of the wall is rounded around the entire perimeter of the hoof. Research in progress Eight Arabian horses were used. These horses had been regularly ridden at the MSU Horse Teaching and Research Center as part of the Department of Animal Science undergraduate horsemanship classes. At the end of spring semester, horses were turned out on pasture and their hooves were allowed to grow relatively long. At the end of the summer, the horses were brought to the McPhail Center. Photographs and radiographs of the hooves were taken and used to measure the size and shape of the hoof and the relationship between the external structures and the underlying 2nd phalanx Lateral cartilage 3rd phalanx (coffin bone) Tendon of deep digital flexor Navicular bone Navicular bursa Figure 4. Illustration of the equine foot depicting at left the anatomical location of the lateral cartilage in relation to the coffin bone and at right the deep digital flexor tendon in relation to the navicular bone and the navicular bursa. bones. Gait analysis was performed by attaching reflective markers to the horse s skin over the head, neck, body and all four limbs and to the hoof wall. Movements of these markers were tracked as the horses trotted along a runway. The data describe movements of the hoof and limb, the force between the hoof and the ground, and torques around the coffin joint. Because the horses used in the study had always been barefoot, their frogs were already quite well-developed, so the heels were leveled to the live sole at the initial trimming. The proper hoof-pastern axis alignment was viewed on x-rays, and the toe was beveled from the white line forward to facilitate breakover and reduce stress on the navicular region. The frog, bars and sole were not trimmed except to remove loose pieces of horn. The horses maintained a regular work schedule throughout the study, performing 1 to 2 hours of work 5 days per week. Hooves were trimmed at 6-week intervals. After 4 months, the horses had a well-developed sole callus, and the bevel at the toe was now taken back to the front of the sole callus (as opposed to from the white line). Every 4 months, the horses returned to the McPhail Center, where photographs and radiographs were taken. Data was collected for 24 months. The most dramatic changes in hoof shape involved the heels. After the heels were lowered, growth and adaptation of the internal structures caused the heel to migrate back underneath the bony column of the limb with a consequent increase in heel angle. At the start of the study the average heel angle was 37 degrees; after 16 months, it was 45 degrees (see Figure 5).

4 MSUE Equine Program Newsletter 4 (Trimming for Soundness, continued from page 3) The angle between the solar surface of the coffin bone and the ground was also monitored. Normally, the heel of the coffin bone is slightly higher than the toe, giving a solar plane angle of about 5 degrees. If the heel is lower than the toe (negative sole plane), it increases tension on the check ligament and the deep digital flexor tendon, thus increasing stress on the navicular region. At the initiation of the study, the average solar plane angle was 3.2 degrees. As the study progressed, the solar angle increased to an average of 7.5 degrees (see Figure 6). Figure 6. Radiograph taken at the initiation of the study (left) and after 16 months of physiological trim (right). The increase in the solar plane angle resulted from the enlargement of the frog (see Figure 7) and increased density of the digital cushion. In addition, other internal structural changes occur, such as thickening of the lateral cartilages with increase in smalldiameter capillary network (see Figure 8) and development of a sole callus in front of the apex of the frog. This callus lies beneath and protects the tip of the coffin bone. Thus, changes in hoof size and shape in response to the physiological trim appeared to indicate internal adaptations that provide support to the coffin bone and improve the shock-absorbing ability of the hoof. Motion analysis is in progress to measure changes in hoof motion and in the torque around the coffin joint. Figure 7. Notice the enlargement of the frog with expansion of the heel on the right compared with the left picture. A Figure 8. Cross-section of hoof showing the lateral cartilage (LC) and the digital cushion (DC). Left depicts thick LC with profuse blood capillaries (dots) and dense DC. Right depicts a foot that carried all the weight on the wall demonstrating thin LC with only a few large-diameter capillaries and a small digital cushion containing much fatty tissue, which is less effective for shock absorption. B This study was funded by the Bernice Barbour Foundation. For more information, visit the Mary Anne McPhail Equine Performance Center Web site. The content of this article is based in part on the following: Biomechanical Effects of the Physiological Hoof Trim Mary Anne McPhail Equine Performance Center Research Report Figure 5. A) foot picture taken at the initiation of the study and B) foot after 16 months of physiological trimming. Physiological trimming for a healthy equine foot Journal of Equine Veterinary Science 23:

5 5 MSUE Equine Program Newsletter Horse Owners Should be Alert for Hoary Alyssum in Pastures Industry Updates As if horse owners don t have enough to think about, with increasing prices for feed, fuel, products and services, fly season in full swing, and continuing challenges with land use and access to trails, they can add awareness of hoary alyssum, a weed that is poisonous to horses, to their list of concerns. Hoary alyssum is found across the northeastern and north central United States and Canada. A member of the mustard family, it produces small, white flowers and can grow 1 to 3 feet tall. Grayish green hairs cover the stems, leaves and seed pods. It is well-adapted to dry conditions and grows in drought-stressed and overgrazed pastures. Some cases of hoary alyssum toxicity in horses have already occurred this year, as a result of horses eating hay cut last year. Horse owners need to learn to identify hoary alyssum and the signs of its toxicity in their animals. Those who may feel that they don t have to worry because they feed supplemental hay and grain should think again: horses on pasture, even if they receive hay and grain, may also graze on hoary alyssum if they find it in their fields. Though it is not preferred horse forage, horses will nibble on it when other plants are not growing because of overgrazing or drought. Toxicity symptoms in horses range from depression to stocking up (swelling in the lower legs), fever and diarrhea. Some horses are extremely susceptible to the toxin, and consumption of hoary alyssum may prove fatal. As little as 10 percent hoary alyssum in one bale of hay may cause problems for some horses. Minimizing problems with hoary alyssum and other weeds begins with good pasture establishment and controlled grazing. When the weed is found in an established pasture, the herbicides that are labeled for its control will also affect forage legumes. If drought conditions have left few other plants in the pasture, removing the animals for the remainder of the growing season is an option. Hay should also be thoroughly examined for the presence of hoary alyssum. MSU and MSU Extension offer a number of droughtrelated resources. For more information about hoary alyssum, horse owners may refer to a fact sheet titled Toxicity, Identification and Control of Hoary Alyssum in Forages. It can be found online at msu.edu/factsheets/hoaryalyssum.pdf and is available at any MSU Extension county office. Images and other information about hoary allysum can also be found on the MSU Diagnostic Services weed and plant identification Web site at edu/weedsplantidentification/hoaryalyssum/tabid/139/ Default.aspx.

6 MSUE Equine Program Newsletter 6 New Clinic for Horses with Back Pain Opens at MSU Oh, my aching back! It s a complaint heard worldwide, and back pain is one of the most common reasons that people go to the doctor or miss work. So, it s not hard to imagine what a horse with back pain might feel like. Unfortunately, very few veterinarians are equipped to comprehensively diagnose and treat back pain in horses. Industry Updates In mid-june, the Michigan State University College of Veterinary Medicine officially opened the McPhail Equine Back Pain Clinic to meet this need. The clinic has a unique combination of professional expertise and stateof-the-art technology that holds great promise for horses with back pain. The clinic s director, Dr. Rob van Wessum, says at least 10 to 15 percent of equine lameness problems can be traced to problems in the back. If we did more research, I wouldn t be surprised to find that the percentage is actually higher, he says. People will often try to treat the lameness as a problem in the leg, when the problem is really in the back. Other performance issues, such as bucking, rearing, stiffness and a general resistance to work can also be signs of a back problem, even if there are no overt signs of lameness, he adds. In the past three years, Van Wessum has worked with about 500 equine back pain cases at the MSU Veterinary Teaching Hospital (VTH) and reports that nearly all are now performing at their original level or higher. By opening a clinic at the VTH specifically devoted to this area, he hopes to bring this success to a wider audience. Van Wessum himself is part of the formula for success. In addition to his 17 years of clinical expertise as a sport horse lameness clinician, he has experience as an internationally known rider, trainer and judge. Combine that with the advanced technology and research available at MSU, and you get dramatic results. Van Wessum uses several types of imaging to help pinpoint problems and treat them more accurately -- fluoroscopy, Doppler ultrasound, bone scans and (soon) MRI. Treatment is followed with a tailor-made rehabilitation program that is designed to increase the horse s range of motion and speed gradually. Client education is an essential part of the program. We show clients anatomical models and videos of how horses move and give thorough explanations during the clinical exam. If they understand why we are prescribing certain rehabilitation techniques, they can, and do, become really committed partners in the rehabilitation process, van Wessum says. He also will work with the client s local veterinarian during the horse s rehabilitation and will provide the vet with a video of the exam and all the information learned during the horse s visit. People are already bringing their horses from around the country to meet with van Wessum, and he makes it as easy for them as possible. We can help arrange transportation with a certified transporter and arrange hotel accommodations, he says. We do all the diagnosis and treatment in a reasonable amount of time, two or three days, so that clients don t find it too hard to stay here with their horses. To schedule an appointment at the McPhail Equine Back Pain Clinic, contact the MSU Large Animal Hospital at

7 7 MSUE Equine Program Newsletter The Facts About 4-H By Taylor Tenlen and Lisa Ondersma Youth Corner First things first: What are the four H s? The four H s stand for head, heart, hands and health they are the cornerstone of the organization s commitment to youth. The 4-H pledge is: I pledge My head to clearer thinking, My heart to greater loyalty, My hands to larger service and My health to better living, For my club, my community, my country and my world. So What is 4-H? 4-H is the largest out-of-school youth program in the United States, with more than 7 million members and 500,000 teen and adult volunteers. You may ask yourself what in the world 7 million people can all have in common? Well, that s the beauty of 4-H it provides opportunities in nearly every area of interest, from fitness and photography to cooking and livestock exhibitions. Groups with similar interests form a club and are organized with the help of a club leader, who is usually an adult volunteer. Club involvement provides opportunities for the development of leadership and citizenship skills, as well as lifelong friendships! The 4-H mission is to empower youth to reach their full potential, working and learning in partnership with caring adults. 4-H has a strong vision for a world in which youth and adults learn, grow and work together as catalysts for positive change. The Michigan 4-H program is part of Michigan State University Extension and has a presence in all 83 counties in Michigan. MSU provides a wealth of information on many areas of interest within 4-H. From on-campus programs such as Exploration Days to off-campus learning opportunities in your own county, MSU and 4-H are helping youth to engage in activities that are both fun and educational. What does 4-H offer the horse lover? One of the best things about 4-H is the broad range of opportunities in each interest area. In addition to county and state fair exhibitions, the 4-H horse and pony program offers numerous educational activities to help members learn more about equines and their care. For example, events such as horse bowl, hippology and horse judging allow 4-H ers to test their equine knowledge outside of the show arena. Many regional and state-level clinics throughout the year provide even more information on the training and care of our four-legged friends. And each club meeting is an opportunity for members to expand their expertise by using curriculum developed especially for 4-H by top professionals in the equine industry. Be sure to visit our Web site, to see what s happening at the state level in 4-H horse programs. You can contact your county Extension office (in the phone book under County Government ) to see what s available in your area and get help finding a club that is just right for you! Interested in becoming more involved? Adult volunteers play a pivotal role in the 4-H program. Volunteers coordinate local community clubs and help to plan and conduct local, regional, state and national 4-H events. Nationally, more than 500,000 teen and adult volunteers share their time and talents with 4-H youth. Interested in volunteering? If so, you can get more information about the application and training process through your local county Extension office. Much of the information in this article can be found at Take a moment to visit this Web site to see what 4-H has to offer you!

8 Equine Program Department of Animal Science Michigan State University 1287 Anthony Hall East Lansing, MI Editorial Board Chief Editor Production & Management Industry News Karen L. Waite, M.S. Horse Health Dr. Judy Marteniuk Research Outlook Dr. Nathalie Trottier Youth Corner Taylor Tenlen Production ANR Communications Printing and Distribution University Relations With summer brings increased outdoor activities. We ll find ourselves visiting the local County Fair, and enjoying the relationship between youth and their horses, but have you ever wondered just what 4-H is all about? We ll be holding our horses for the farrier, but have you pondered the physiological effect of trimming on your horse s feet? We may find ourselves inspecting our pastures for toxic weeds, but have you considered what might happen if your horse eats those plants? Answers to these questions and more can be found in this edition of the Equine Newsletter, so slather on the sunscreen, put on your sunglasses, pour a glass of iced tea and ENJOY! Letter from the Editor Sincerely, Karen L. Waite, M.S kwaite@msu.edu Calendar July MSU All Arabian Horse Show MSU pavilion Paula Hitzler, Ag Expo MSU campus August State 4-H Horse Show MSU pavilion September 10, 17, 24 Equine Forage from One End to the Other Workshop Novi, Carla McLachlan, For more information, go to the Web at Or call the MSU Equine Program office at MICHIGAN STATE U N I V E R S I T Y EXTENSION For more information, call the MSU Horse Extension office at or check the Equine Extension Web Site: MSU is an affirmative-action, equal-opportunity employer. Michigan State University Extension programs and materials are open to all without regard to race, color, national origin, gender, gender identity, religion, age, height, weight, disability, political beliefs, sexual orientation, marital status, family status or veteran status.

9 Understanding Equine Forage Management From One End to the Other! Equine Pasture, Hay and Manure Management Series Wednesdays: September 10, 17 and 24 6:30-9 p.m. MSU Tollgate Center 2815 Meadowbrook Novi, MI Cost: $75 For additional information, call Week 1 - September 10: Pasture Management This session will cover strategies to establish, renovate, maintain and better utilize horse pastures. Toxic plant concerns will also be discussed. Week 2 - September 17: Hay Selection and Management This session will focus on criteria for selecting quality hay for horses and ponies and storage and utilization to help reduce the amount of hay needed. Week 3 - September 24: Manure Management This session will cover the environmental regulations that pertain to your farm and strategies to help handle manure and bedding. Name: Address: City: State: Zip: Telephone: Visa MC AMEX Discover Cardholder name: Card number: Exp. date: Address: City: State: Zip: Registration is due September 1, Make checks payable to Michigan State University and send to MSU Equine Programs, 1287 Anthony Hall, East Lansing, MI