IN-DEPTH: LAMINITIS FOR THE PRACTITIONER Farriery Options for Acute and Chronic Laminitis Stephen E. O’Grady, BVSc, MRCVS; and Andrew H. Parks, VetMB, Diplomate ACVS Authors’ addresses: Northern Virginia Equine, PO Box 746, Marshall, VA 20116 (O’Grady); and Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA 30602 (Parks); e-mail: [email protected] (O’Grady). © 2008 AAEP. 1. Introduction placed on or within the hoof capsule. Approaches Laminitis is a frustrating and disheartening disease to treatment should be based on anatomical or me- to manage. The greatest challenge to both veteri- chanical principles aimed at what we want to accom- narian and farrier is to limit structural damage in plish on a given laminitic foot rather than any one the acute stage of the disease and to improve func- method of farriery. This paper will address the tion in affected feet that may have substantial and various farrier methods that are used routinely to possibly permanent structural changes. It should treat both acute and chronic laminitis. It is imper- be remembered from the onset that it is the extent of ative that medical, metabolic, environmental, and the lamellar pathology that will influence not only dietary issues be addressed concurrently with foot our ability to treat a horse with laminitis but also management in laminitis. Successful treatment is the eventual outcome of a laminitic case.1,2 If this invariably enhanced by merging the veterinary and was not true, we would not continue to observe the farrier expertise to gain the very important owner enormous number of horses that are adversely af- compliance. fected by laminitis. Treatment regimens for both acute and chronic laminitis generally remain em- 2. Acute Laminitis piric and are based on the past experience of the Three fundamental issues exist when presented attending clinician/farrier. Each case of laminitis with a patient with acute laminitis. The initial should be approached on an individual basis noting issue is that the examiner has no accurate means of the predisposing cause, the clinical signs, examina- knowing the extent of the laminar damage present tion, movement, foot conformation, and the struc- and thus is unable to predict the future with reason- tures of the foot that can be used to change the forces able accuracy. All cases of acute laminitis should be treated as an emergency and monitored closely. The number of horses that have suffered a severe Portions of this manuscript have been adapted with permission episode of acute laminitis that are treated success- of the editors from Parks AH, O’Grady SE. Chronic laminitis. fully is difficult to determine, but, in the authors’ In: Robinson NE, Sprayberry K, eds. Current Therapy in experience, this number is at best low to modest. Equine Medicine, Vol 6. St. Louis, MO: Saunders (in press). The window of opportunity for treatment once clin- NOTES 354 2008 ր Vol. 54 ր AAEP PROCEEDINGS IN-DEPTH: LAMINITIS FOR THE PRACTITIONER Fig. 1. (A) Shows the load being placed directly on the lamellae when there is a shoe on the hoof or the horse is standing on a hard surface. (B) Shows the load being shared with structures on the ground surface of the foot when the horse is placed on a deformable surface or if a deformable material is placed on the ground surface of the foot. ical signs are apparent and a diagnosis has been shod and apply some type of deformable material to made is relatively short. It is well known that the the solar surface of the foot such that the sole, bars, onset of cellular injury within the lamellae occurs and frog in the palmar/plantar section of the foot during the developmental stage of laminitis and pre- become load sharing with the hoof wall (Fig. 1, A and cedes the onset of pain and lameness. Cellular B). Frog support by itself has become ingrained in damage can exist for a period of time before the the veterinary and farrier literature as such a horse, owner, and veterinarian are aware that lami- method to support the weight of the horse. The nitis exists. Laminitis frequently stems from a sys- anatomy of the bottom of the horses’ foot is such that temic response to a disease process in an organ the horny frog (which varies in thickness) and the system remote from the foot such as the gastrointes- digital cushion above it are both readily compress- tinal, respiratory, reproductive, or endocrine sys- ible structures under pressure. When pressure is tems. Therefore, medical treatment during the placed over the frog, it quickly deforms and is com- acute stage needs to aggressively address the initi- pressed, and the interface between the ground sur- ating cause of laminitis or if treatment of the cause face of the frog and the solar surface of the distal was initiated before the onset of laminitis, it should phalanx (P3) is diminished. The frog can be irre- be continued. versibly damaged by applying this focal pressure, Second, there is no practical means to counteract and in some horses, it can and will cause increased the vertical load of the horse’s weight that is placed pain/lameness.a It is the author’s belief that frog on its feet.2 The mass of the horse can only be support alone is not beneficial. In the author’s ex- slightly altered, and no method of so-called foot sup- perience, it is more advantageous to recruit the en- port will alter the vertical load. If the horse is shod tire solar surface in an attempt to reduce the or if the horse stands on a hard surface, weight mechanical stresses on the lamellae. This can be bearing is concentrated around the perimeter of the accomplished by applying either thick styrofoam, hoof onto the compromised lamellae. In acute lami- one of the deformable silicone impression materials, nitis, it may be appropriate to remove the shoes if or removable boots that contain an insert, or by AAEP PROCEEDINGS ր Vol. 54 ր 2008 355 IN-DEPTH: LAMINITIS FOR THE PRACTITIONER laminitis, but it limits the evaluation of the distal phalanx to one plane. It does not allow identifica- tion of asymmetrical medial or lateral distal dis- placement of the distal phalanx. Therefore, the authors consider it crucial that a dorsopalmar (dorso 0° palmar) radiographic projection be included as part of the radiographic study for either acute or chronic laminitis.3 Quality radiographs are needed to visualize the osseous structures within the hoof capsule and the hoof capsule itself. Radio-opaque markers can be used to determine the position of the distal phalanx in relation to surface landmarks. Fig. 2. Radiographs illustrate severe distal displacement of the Baseline radiographs should be taken in the acute distal phalanx 7 days after showing the onset of acute laminitis. stage of laminitis and can aid the diagnosis by mea- suring the distance between the outer hoof wall and the parietal surface of the distal phalanx, as well as placing the horse in sand. It should be noted that assessing hoof capsule conformation to determine when using sand, “beach” sand rather than con- whether trimming changes are necessary. struction sand is preferable because of its ability to The radiographic features of chronic laminitis are conform to the bearing surface of the feet and not well documented.4 The following observations pack. Applying shoes in the acute stage of lamini- from the lateral radiograph are important in deter- tis has not been shown to offer any advantages. mining the prognosis and guiding treatment: the The third factor is the distractive forces on the thickness of the dorsal hoof wall, the degree of dorsal lamellae caused by the moment about the distal capsular rotation, the angle of the solar surface of interphalangeal joint associated with tension in the the distal phalanx relative to the ground, the dis- deep digital flexor tendon (DDFT). In the acute tance between the dorsal margin of the distal pha- stage, this can be countered to some extent by pro- lanx and the ground, and the thickness of the sole. viding mild heel elevation and by moving the break- The dorsopalmar radiograph is examined to deter- over in a palmar/plantar direction. Raising the mine the horizontal position of the distal phalanx in heels excessively in the acute stage has been advo- the frontal plane. Asymmetrical distal displace- cated by some, but in our experience should be done ment of the distal phalanx on either the lateral or with caution because there is no factual evidence to medial side is present if an imaginary line drawn substantiate a beneficial effect.1 across the articular surface of the distal interpha- Distal displacement (sinking) of the distal pha- langeal joint or between the solar foramens of the lanx occurs when the entire lamina attachments are distal phalanx is not parallel to the ground, the joint sufficiently damaged allowing the distal phalanx to space is widened on the affected side and narrowed displace uniformly within the hoof capsule (Fig. 2). on the opposite side, and the width of the hoof wall There is minimal involvement of the DDFT during appears thicker than normal on the affected side. the process of distal displacement. A common If the position of the coronary band is visible on the treatment regimen for distal displacement is to raise radiograph, the distance between the coronary band the heels with the theory that it decreases stresses and the palmar processes of the distal phalanx will on the DDFT; a practice that the authors have not be greater on the affected than the unaffected side seen to be successful.