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.
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.
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.
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.
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.
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.
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 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