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- Dr. Redden's Equine Podiatry Course (Jul 26-30, 2021)Tickets: $512.50 - $2,767.50July 26, 2021 | 12:00 PM8235 McCowans Ferry Rd, Versailles, KY 40383, USA
- Dr. Redden's Equine Podiatry Course (Sept 6-10, 2021)Tickets: $512.50 - $2,767.50September 6, 2021 | 12:00 PM8235 McCowans Ferry Rd, Versailles, KY 40383, USA
- Shoeing the Laminitic Horse
SHOEING THE LAMINITIC HORSE R. F. Redden, D.V.M. P.O. Box 507 Versailles, Kentucky 40383 Reprinted with permission from the American Association of Equine Practitioners. Original printed in the 1997 AAEP convention proceedings. INTRODUCTION: Laminitis is a complex disease syndrome often seen subsequent to a variety of primary diseases. The prognosis ranges from good to grave and is dependent on the degree of damage to the vital supporting structures and mechanical stability of forces perpetuating displacement of PIII. This syndrome demands the expertise of professional farriers, as well as veterinarians as therapeutic shoeing plays a major role in the successful treatment of the majority of laminitic horses. Treatment length can vary from a few weeks to years, requiring commitment and dedication for seemingly endless maintenance regimes. Establishing an effective protocol to treat laminitis will improve the treatment regime and help farriers and veterinarians gain good experience. Success rates vary from horse to horse and are greatly influenced by the ability of veterinarians and farriers to assess the damage, read the particular needs and treat the syndrome with a progressive attitude, built on knowledge of the subject and professional camaraderie. INITIAL EXAMINATION: Obtain a good history and carry out a thorough physical examination to include radiographs on the first visit. Laminitis often follows other primary disease maladies, such as colitis, pneumonia, pleuritis, retained placenta, dystocia, potomac fever, blister beetle ingestion, protracted diarrhea, salmonella, selenium toxicity, fescue poisoning, injudicious use of corticosteroids, stress, contra limb acute lameness and others. Be alert to the hoof characteristics that vary from normal, both grossly, as well as radiographically. Being focused on details will help rule out other acute foot problems that closely mimic the signs of laminitis. TAKING RADIOGRAPHS: A methodical, disciplined technique assures consistent, good quality, pure lateral projection. Soft detail images reveal anterior-posterior balance and the relationship of PIII to horn and horn to load. These parameters must be clearly demonstrable as they become an essential guideline for pathological shoeing. Most professional farriers have become quite proficient reading good quality, soft tissue detail film, as it relates to their task of re-establishing a meaningful equilibrium. Films taken before and after each shoeing session tremendously increase the knowledge bank and efficiency of farrier and veterinarian and consequently improves the prognosis. Practice tips that have improved my technique: Pure lateral, primary beam strikes the foot in a horizontal plane, just above the ground surface. Zero film, subject distance. Opaque marker, detailing the face of the horn wall, as well as ground surface. Positioning block, 3 x 5 x 7, with a wire running through the long axis is compatible with most all x-ray machines. RADIOGRAPHIC INTERPRETATION: The distance from the face of PIII to the outer horn wall is referred to as horn-lamellar space. Become familiar with normal parameters. Most light breeds will measure 15 to 17 mm., heavy, older broodmares, stallions and most Standardbreds will measure 20 to 22 mm. Base line views become most valuable as they establish a starting point. The depth of sole and cup directly beneath the apex of PIII is quite easy to monitor with pure lateral films. Extensor process relationship to coronary band varies from horse to horse and foot to foot. Rely on the base line film to assess starting location. CLASSIFY THE DAMAGE: Rotation is significant with acute cases but is very misleading with chronic cases due to abnormal horn growth. Classify the damage before establishing protocol. A scale of 1 to 1000 offers a realistic classification system for all laminitic cases. Classify each horse at onset based on history, physical and radiographic examination. Design therapy to reverse forces at play and meet the needs of the patient. This system enables me to treat not only each case but each foot as a separate entity and to better explain the seriousness of the syndrome to my clients. TREATMENT: Acute laminitis should be considered an emergency because the window of maximum response closes rapidly. Sound mechanical therapy applied in a timely fashion can be very effective against secondary compressive damage seen subsequent to displacement of PIII. Preventing and or minimizing displacement in the face of this syndrome can alter the course of the disease. THERAPEUTIC: Treat the whole animal, address primary problems when known. Use anti-inflammatories with discretion. Phenybutazone remains the drug of choice. Many others have good to excellent anti-inflammatory properties and can be useful. Nitroglycerin creams and patches have been advocated recently and may have potential. Caution; use with discretion and be judicious. Teach proper use and handling of these products as they have precautions and contra indications. Apply emergency aid designed to significantly reduce deep flexor pull, Modified Ultimates, Advance Equinea. The clinical response will aid in assessing soft tissue damage. Before applying any therapeutic device become familiar with the specific conformation characteristics of each foot. Learn to read positioning of PIII within the capsule with the aid of radiographs as well as without. Three basic principles are very effective against deep flexor pull as it opposes diseased laminae: Raising the heel 10 to 18 degrees significantly reduces pull on the tendon. Placing breakover directly beneath the apex of PIII, (phalangeal point of rotation), eliminates opposing lever arm and significantly reduces lamellar stress and sub solar compressive forces. Utilizing sole, frog, bars and sulci as uniformly loaded support zones. Success with mechanics lies in applying a device that meets the specific needs of each foot. Years of experience are required of veterinarians and farriers to properly read feet. A common error is to lump all feet and all cases in a basic category. This philosophy fails to produce favorable results the majority of the time. Very basic guidelines to help load the heel and unload the apex and laminae: When rotation is present the hoof capsule must be trimmed in a fashion that re-aligns PIII with the natural load surface, otherwise the apex of PIII continues to compress sole corium, further compromising circulation. Trim the heel parallel to the freshly trimmed frog starting at a point just behind the apex of the frog. Rasp the heel down at the base until good, sound horn tubules are evident at the widest point of the frog. Use discretion as over trimming can produce harmful results. The horn capsule forward of the apex of the frog will not make contact with the shoe, therefore we are shoeing to the heel, not the toe. All nails must go behind the widest point of the hoof in order to secure the shoe to the heel. Re-alignment normally increases deep flexor pull depending on severity of displacement, hoof angle, heel angle and breakover placement. Raising the heel once properly derotated increases load to the heel area and reduces tendon pull influencing sole corium and lamellar perfusion. Leave all the sole and foot mass possible as it is natural protection and desperately needed. Design the shoe so breakover is 3/4 of an inch forward of the true apex of the frog. Note; many times the frog will lay on top of the sole giving false impression of the true location. Trim the toe at a 45 degree angle with the ground surface to avoid breakover contact. Stay well forward of the natural sole. Resilient custom fit arch support offers a broad spectrum, evenly distributed support surface that reduces load on the diseased laminae, Advance Cushion Supportb . Strict stall rest throughout the recovery period reduces unwarranted stress on the healing laminae. Note; recovery period is dependent on damage. Cases with significant rotation and/or sinking must re-establish lamellar integrity or relatively normal horn growth pattern and a dense sole to reach optimum recovery, six months to one year is a normal recovery period. UNFAVORABLE TREATMENT RESPONSE: When faced with an unfavorable response take lateral radiographs with the shoes on. Routinely taking films following every therapeutic shoeing and focusing on small details improves the end result. Check for proper derotation, mass of heel, sole impingement, progressive displacement (rotation, sinking and lamellar thickening). Keeping in mind the normal, evaluate the coronary band and look for sensitivity, discoloration, moisture and abscessation. Take dorsal-ventral views, look for pathological solar fractures. A venogram of the digit is a helpful aid for determining circulatory damage1 & 2. Classic sinkers have a stark loss of contrast throughout the laminae, sub solar area and within the semilunar canal. Subsequent venograms can aid in assessing progress with cases showing marginal loss of contrast on the initial examination. When faced with a poor or slow response following proper derotation and shoeing, consider deep flexor tenotomy as an adjunct to therapy. Deep flexor tenotomy should be considered a viable means of treating complicated laminitis. Proper derotation, shoeing and timely surgery can offer penetrated laminitic cases full recovery. THERAPEUTIC SHOEING: Therapeutic shoeing is indicated for laminitic cases that develop five degrees of rotation or greater and all with sinking of any degree. Progress in the field of pathological shoeing has accelerated over the past ten years due to combined efforts of farriers, veterinarians and research. Currently I prefer to fabricate a four point rail shoe, similar to the shoe by Gene Ovnicek3 . I have modified the concept to increase toe protection and applied a sole to ground resilient arch support. There are many ways to make this shoe. Farriers need to know the basic principles of construction and application. Breakover is at the widest point of the foot, just in front of the apex of the frog. Rails reduce tendon pull and enhance medial-lateral breakover. Arch support offers broad spectrum support to the sole, frog and bars. Properly placing the shoe on a derotated laminitic foot with adequate mass of heel can offer a more consistent measure of successfully treating laminitis. The shoe has offered a favorable response for sinkers and cases with penetration. This shoe and technique enhances the effects of deep flexor tenotomies. CONCLUSION: Ninety-four horses were shod with four point rail shoes with Advance Cushion Support. 75 had greater than ten degrees rotation. 38 had greater than 1 centimeter of sinking. 40 penetrated the sole. 38 treated with deep flexor tenotomy. RESULTS: Twenty-four returned to previous status.Of these twenty-four there were seven broodmares, one stallion, one Arab show horse, one Quarter Horse, one Paso Fino, five Walking Horses, one Saddlebred, one Morgan, one Show Hunter, two riding horses, three were penetrated; one Paso Fino, one Walking Horse and one Thoroughbred broodmare. Thirty-one returned to pasture soundness. Sixteen were penetrated, three Saddlebreds, one Arab, four Thoroughbreds, two Quarter Horses, one Standardbred, four Walking Horses and one Morgan. Nineteen were euthanized. Nine sinkers with penetration, one penetration and nine chronic cases with extensive osteomyelitis. Thirteen could not be located for follow-up. REFERENCES: 1. R. F. Redden, D.V.M. The Use of Venograms As A Diagnostic Tool. Bluegrass Laminitis Symposium, 1993. International Equine Podiatry Center, P.O. Box 507, Versailles, Kentucky 40383. 2. Chris Pollitt, DVM. Personal communication. University of Queensland, Saint Lucia, Queensland 4072, Australia. 3. Gene Ovnicek. 525 Half Moon Road, Columbia Falls, Montana 59912. FOOTNOTES: a. Modified Ultimates. Advance Equine, P.O. Box 54, Versailles, Kentucky 40383 b. Advance Cushion Support. Advance Equine, P.O. Box 54, Versailles, Kentucky 40383
- Identifying and Treating Canker
Indepth Equine Podiatry Symposium Notes Written and presented January 2009 by R.F. (Ric) Redden, DVM Canker foot carries a wide variety of meanings. The basic characteristics of the disease are white, proliferative finger-like projections along the coronary band, a musty (fungal) odor and/or deep necrotic, non-sensitive involvement of the sensitive frog, digital cushion, sole corium and laminae. There is very little if any useful data in our current text books to help define the various stages of canker or the many different forms it can manifest. Older texts written before veterinary medicine was a reality are also vague, designating many different pathological processes as canker. Canker falls under the broad category of pododermatitis, which is descriptive to some degree but very misleading for the case with very extensive necrotic damage to the deep structures of the foot. The fact is, this disease occurs throughout the world yet remains quite a mystery, as we do not understand the challenges of the various forms that all appear to be related. Over the years I have dealt with many cases categorized as canker, from its initial to advanced stages. Incidence Contrary to popular belief, in my experience this disease is not limited to horses kept in low hygiene conditions. Some of my most difficult cases have come from top level racing and training stables that maintain the highest level of hygiene. It does not appear to be contagious either, as I have only seen one instance in which more than one horse from the same farm or stable developed canker. In that case, several show quality Clydesdales were presented to me with very extensive, advanced lesions, some in one foot and others in all four. They were from a farm in Ohio that had previously been a major hog farm, but any possible connection would be speculative. Draft breeds are apparently more prone to canker, possibly because of the long feathers and dense, coarse hair that is characteristic of the breed. The lack of air to the skin in the lower leg and coronary band along with the cumulative effects of bacteria and fungus that persist in this area could be a direct cause of the increased incidence in these breeds. However, it certainly does not explain why other breeds that have extremely short hair and often get daily baths can have such a serious incident, often appearing to originate within the digital cushion and frog sulcus. I have seen this condition in warm bloods, Thoroughbreds, Standardbreds and only a few mixed breeds. Possibly other breeds have this condition with the same incidence, but I cannot say that from experience. Clinical Differences Between Thrush and Canker During the initial stages of canker, most horsemen almost invariably feel they are treating thrush that simply won't go away. The majority will use caustic agents to dry it up, which works quite well in most thrush cases. However, when canker is the culprit, products that burn or cauterize the sensitive tissues seal the canker inside, frequently causing it to spread throughout the digital cushion. Thrush is caused by an organism initially referred to as xerophilic Nectria, but now called spirochaeta. Both terms have destructive connotations, but they are simply low virulent organisms that have frog lysing properties when conditions allow them to multiply. Thrush starts along the sulci of the frog. The deep crevasse that appears periodically in a variety of foot stereotypes can harbor moisture and causative organisms that find it ideal for growth. The result is thrush. The area is tender to a hoof pick but does not cause a lameness concern. The unpleasant odor is typical of this organism. Canker also has a rank odor, but it is more of a musty odor that we commonly find when fungi are involved. Characteristics Canker appears in many forms and has been thought to involve the skin of the lower leg as well as the foot. I will focus on the disease as it affects the foot. Canker may involve one foot or all four. The very mildest form appears as an inflamed coronary band with a villainous growth of tissue that appears as soft, white projections with a fungal odor. More extensive cases can have a non-sensitive, necrotic appearance that can destroy the sensitive frog, digital cushion and sole corium in various degrees. It can also appear as a yellow, cheesy layer of tissue that involves the sensitive frog and digital cushion. Both problems get very little respect at the onset as the horse is not lame. Thrush can be successfully treated simply by cleaning up the foot with soapy, hot water and packing dry gauze in the deep confines to prevent air from getting to the deeper areas. I prefer to use a 50/50 solution of iodine and glycerin to treat thrush, as it doesn't burn the tissue and quickly kills surface organisms. Canker on the other hand, does not respond to this treatment, and as stated goes rampant when sealed behind caustic burns. When canker appears in the heel area or reaches the surface through an existing quarter crack or angle of the heel, some may mistake it for an abscess and treat it as such. However the horse seldom shows any sign of lameness and a large majority of cases continue in training relative to the size and extent of the lesion. This is non-typical of any and all abscesses that most always cause a painful response. Etiology As a rule, it is helpful to know what organism we are dealing with, but with canker that remains a mystery. We can culture corneybacteria, which is most likely a contaminant. Spirochaetas are also routinely found within the necrotic tissue. Other researchers say it closely resembles neoplasm. The bottom line is that we have no clue how this problem starts or why it is manifested in so many different forms. Treatment Mild invasion In the early stages the hair along the bulbs of the heel and coronary band will stand out instead of lie down over the coronary crest. Looking closely you will see small, white hair-like projections that can easily be removed with an abrasive cloth or tool. There is a distinct odor typical of fungi once this tissue is debrided. The hair-like projections can be removed every day and still reappear the next. The coronary band can also appear quite hyperemic and can easily bleed with abrasive massage. When this stage appears it behooves us to closely examine the frog and adjunct horn tissue for any involvement. Often the organism will be embedded deep within the sensitive frog and digital cushion and can only be detected in a very small area on the surface. Clean hooves daily with hot, soapy water. Physically remove the surface hair-like projections with abrasive action. Cover the diseased area with a thin coating of tetracycline sulfamethazine paste. Tetracycline is apparently effective in eliminating the spirochaeta, and SMZ is a broad spectrum antibiotic for commonly found bacteria. This product was developed by my colleague, Dr. Carrie Long, and I now use it on all my cases. Moderate invasion A small, thumb-sized area of tissue with a yellow, cheese-like appearance that does not appear to be part of the frog or digital cushion is indicative of a more moderate invasion of canker. This area needs to be surgically removed to include a couple of millimeters of surrounding healthy tissue. I have had little luck being conservative when the digital cushion is involved. On occasion, even the smallest surface area will only be the tip of the iceberg. The entire frog and a large majority of the digital cushion and sole corium and even laminae in the heel and quarter area may also be involved. Apply a hospital plate shoe prior to surgical debridement. The plate serves as a bandage and offers a means to apply pressure to the surgical site, which is a prerequisite for healing. Pressure also suppresses granulation tissue. I've found this to be one of the most important aspects of treatment. Using a tourniquet and local anesthetic, surgically remove all diseased tissue plus a thin layer of healthy tissue. Pack the area firmly with gauze soaked in 2% Betadine. Change it daily. Severe invasion When the non-sensitive frog and surrounding horn is undermined, the organism has most likely penetrated deep within the foot. It is not uncommon to expose the DDF simply by debriding with dry gauze. I often wonder how the horse can remain non-painful as such a devastating organism destroys the foot. Trim the foot, avoiding all necrotic tissue until the shoe is applied. Apply a hospital plate that reaches up around the bulbs of the heel. This is important as most advanced cases also involve the bulbs, necessitating firm pressure post surgery. Sedate the horse and block the foot with an abaxial block.Apply a tourniquet. Using a pair of Allison forceps snapped onto the tissue that needs to be removed, start in one area and attempt to dissect the diseased tissue from the underlying healthy corium and cushion, taking approximately 2mm of healthy tissue. Removing it in one piece greatly facilitates our ability to get all of the diseased tissue. Know before you start that this is not a little debridement. You may be removing a large majority of the structures of the entire posterior half of the foot. Be very careful not to involve the navicular bursa, tendon sheath or coffin joint. Pack the area with 2% Betadine soaked gauze and fill the remainder of the area with Advance Cushion Support before applying the hospital plate. Note there will be considerable hemorrhage once the tourniquet is removed. I prefer to over-pack the foot for the first few hours post op, then remove a very small area of gauze or trim the plate side of the ACS. We need the excess packing only until hemorrhage has ceased. Too much pressure for 24 hours traumatizes the sensitive tissue, but too little allows granulation tissue to grow rampant. Experience will help you get it just right. Remove the plate, rubber and gauze on day two. I prefer peroxide as a means to soften the clot adhering the gauze to the sensitive area. Make a paste using LA 200 tetracycline and SMZ tablets. Put a thin layer on a gauze pad and cover the area. Fill the remainder of the foot with ACS. Cut the bottom 1/3 of the ACS off with every change and add a new layer of ACS that will fit the conformation of the surface as it heals. Then make a new filler pad when indicated. This continually suppresses granulation. Keeping direct but firm pressure assures optimum results. The most severe case requires a minimum of 60-90 days to heal. Most cases go on to be sound athletes. Occasionally the growth centers of the horn are drastically distorted, resulting in a variety of horn growth abnormalities. This sounds like a radical approach to a problem that doesn't make the horse lame. Keep in mind the majority of my cases have come to me as a last resort following months of more conservative treatment.
- Ensuring High-Quality Radiographs of the Equine Foot
Dr. Redden's Notes Ensuring High-Quality Radiographs of the Equine Foot Written by R.F. (Ric) Redden, DVM Radiographic examination of the equine foot can provide a wealth of information when performed in a methodical manner. There is no single protocol that is suitable for every case, but the same basic approach applies to every radiographic examination. Preparation The foot should be thoroughly cleaned of all debris, including any material that may have lodged in the sulci of the frog. The shoe may need to be removed for a complete digital study; however, it can be left in place for lateral, dorsopalmar (DP), and 65-degree DP views. In fact, leaving the shoe on can provide useful information. Also, in very lame horses leaving the shoe on minimizes pain and saves time and expense. The surface of the dorsal hoof wall should be delineated from the top of the wall to the toe using a radiopaque material, such as contrast paste. To facilitate uniform views, the horse's feet should be placed on wooden blocks (one block under each foot). Equipment and Exposure Factors Obtaining consistent, high-quality radiographs requires familiarity with the radiographic equipment. It is well worth taking the time to formulate a detailed technique chart for the x-ray machine, film-screen combination, and processing method you routinely use. Two exposures should be taken for each view. The author uses the following terminology for exposure factors: "soft" (for nonbony tissues), "medium" (for bone of moderate density), and "hard" (for dense bone). Specific exposure factors will vary with the equipment used. Soft tissue detail is essential on at least one film per view, as the nonbony tissues surrounding the distal phalanx are an integral part of all foot problems. However, it is important to establish a range of normal for different breeds and age groups. Routine Views Accurate positioning is as important as the exposure factors used. For the lateral view, the x-ray beam is aimed 1–2 cm above the bearing surface (i.e. at the level of the apex of the distal phalanx), midway between heel and toe. The beam must be horizontal and perpendicular to the sagittal plane of the foot. The two exposures recommended for this view are soft and medium. For a lateral view of the navicular bone, the beam is centered approx. 5 cm (2 in) higher and further toward the heel (i.e. over the navicular bone). The two exposures recommended are medium and hard (using a 6:1 parallel grid). For the DP view, the horizontal beam is centered at the toe, again at the level of the apex of the distal phalanx. The two exposures recommended are soft and medium. The same exposure factors can be used for the 65-degree DP. For evaluation of the navicular bone on this view, the beam is centered over the navicular bone and a hard exposure is taken using a grid. To prevent distortion of the distal phalanx on any of these views, it is important to ensure that the cassette is in contact with the foot and the beam is perpendicular to the cassette.