UNCORRECTED PROOF The Long-Term Results of Glue-on Shoes on Dorsal Hoof Wall Distortion P.T. Reilly, a D.A. Reilly, PhD, a,b and J. Orsini, DVM, ACVS a ABSTRACT Every equine hoof has a certain amount of distortion. This presents in various forms: flares, dished toes, under-run heels, and cracks. Several farrier texts anec- dotally suggest a correlation between hoof capsule dis- tortion and lameness. The goal of this study was to evaluate the effects of the Sigafoos Series I glue-on shoe on hoof capsule distortion, and specifically, the effect on dorsal wall deviation. Measurements of the hoof were made using the Metron hoof evaluating sys- tem by Eponatech. Comparisons were made of the fol- lowing values: dorsal length, hoof angle, dorsal wall deviation, hairline angle, hairline deviation, heel/toe height, heel height, heel angle, and support length. The study group consisted of front feet of horses shod exclusively in the Sigafoos glue-on shoe for a period of 1 year, and the control group consisted of 133 front feet from horses using nailed on shoes for a similar period and with a musculoskeletal complaint. The results indicate a 48% reduction in dorsal wall deviation for the study group. This finding supports the use of this glue-on shoe as beneficial with the goal to reduce capsu- lar distortion of the dorsal wall. Keywords: Horse; Horseshoe; Glue; Distortion; Hoof wall INTRODUCTION Distortion of the hoof capsule has long been hypothesized to be either a direct cause of equine lameness, or a patho- logic condition associated with a chronic degenerative con- dition. Several recent studies have implicated hoof capsule distortion as a contributing factor in equine lameness. For example, in managing chronic laminitis, the mechanical failure of the foot and subsequent hoof distortion has been shown to serve as a major limiting factor to successful rehabilitation. 1 Distortion in the form of under-run heels has been associated with the frequency of catastrophic musculoskeletal injuries. 2 Stabilization of the hoof, how- ever, has been suggested as a goal in the treatment of var- ious acute injuries, including hoof wall resections, coronary avulsion, and toe and quarter cracks that otherwise can lead to distortion of the hoof. The purpose of this study was to assess the effects of the Sigafoos Series I glue-on shoe with respect to capsular dis- tortion, and in particular its effect on dorsal wall deviation. HYPOTHESIS Practical experience indicates that the absence of nails alone increases the integrity of the hoof capsule and therefore reduces the amount of wall deviation. Research using strain distribution tests have shown a steep strain gradient associ- ated with defects such as cracks and unstable nail holes. 3 When combining this with the presence of polymethylme- thacrylate and the reinforcement of the fabric cuff, there is reason to believe that the Sigafoos shoe adds to the overall integrity of the hoof wall, versus a nailed-on shoe, which would detract from overall wall strength. Dishing of the dorsal wall indicates a prior rotation of the distal phalanx or a flexural deformity involving the deep digital flexor tendon. 4 At a more subtle level, dishing has been explained as a tearing of the laminae at the toe, 5 pre- sumably attributable to excessive stress of the deep flexor tendon during locomotion. This can lead to lameness if un- treated, because the breakover point and the entire base of support move cranially. Recent studies have explored the deformation of the dorsal wall while under this stress. 3,6 During the stance phase of locomotion, the dorsal wall rotates caudoventrally along the distal border. This degree of movement may be quantified to be as high as 0.92 mm in the dorsal wall. 7 The dorsal wall has been shown to be thicker and more rigid than the wall at the medial and lat- eral quarters. This is believed to protect the adjacent inter- nal sensitive structures. 8 It therefore appears beneficial to externally reinforce the structure of the hoof wall to mini- mize stress in the sensitive structures and the chronic path- ologic conditions associated with distortion of the dorsal wall. In this study, the following hypothesis was tested: The Sigafoos glue-on shoes decreases dorsal hoof wall deviation. From the Department of Clinical Studies—New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA a ; and Niagara University, NY b . Reprint requests: Patrick T. Reilly, School of Veterinary Medicine, University of Pennsylvania Department of Clinical Studies, New Bolton Center, Kennett Square, PA 19348. 0737-0806/$ - see front matter Ó 2009 Elsevier Inc. All rights reserved. doi:10.1016/j.jevs.2008.12.010 FLA 5.0 DTD  YJEVS834_proof  9 January 2009  2:24 am  ce 17 ARTICLE IN PRESS 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 Journal of Equine Veterinary Science  Vol -, No - (2009) 1