EQUINE VETERINARY EDUCATION Equine vet. Educ. (2020) 32 (8) 415-423 doi: 10.1111/eve.13031


Original Article The proper application of the wooden shoe: An overview


S. E. O’Grady Virginia Therapeutic Farriery, Keswick, Virginia, USA Corresponding author email: sogrady@look.net


Keywords: horse; hoof; therapeutic farriery; lameness; laminitis


Summary The wooden shoe provides the clinician with an alternative option to conventional farriery when treating a variety of foot problems such as acute/chronic laminitis, white line disease, distal phalanx fractures and poor-quality hoof capsules. The wooden shoe provides a simplified method to apply many of the principles of therapeutic farriery which include redistributing the load or forces on the foot, repositioning breakover and providing heel elevation when necessary. Understanding the biomechanics of the wooden shoe along with understanding good basic farriery which include the appropriate foot trim, proper size, fit and placement of the wooden shoe on the foot combined with the appropriate application are essential for consistent success. This paper outlines what is considered to be the proper application of the wooden shoe.


Introduction


There are many practical farriery options available to the clinician when an alternative to a horseshoe may be necessary or preferred. The wooden shoe has become a simple, practical and very effective farriery option for treating not only chronic laminitis but a variety of other foot problems (Steward 2003; O’Grady et al. 2007; O’Grady and Parks 2008; O’Grady and Steward 2009; Parks and O’Grady 2009, 2015; O’Grady 2010, 2011) (Fig 1). Among those problems that may benefit from the wooden shoe are acute/chronic laminitis, extensive white line disease, fractures of the distal phalanx/navicular bone and horses that have feet with thin deformable soles. The wooden shoe should only be used as a transitional device to stabilise the hoof capsule, promote hoof wall growth at the coronet and increase sole depth. Once the structures of the hoof capsule have improved with sufficient mass to achieve stability and realignment of the distal phalanx within the hoof capsule in the case of chronic laminitis, conventional farriery is used or the horse can be left barefoot. The wooden shoe is simple to apply but, as with any procedure, there is a learning curve such that it is essential to follow a procedural model. Understanding the biomechanics of the wooden shoe coupled with understanding good basic farriery which include the appropriate foot trim, proper size, fit and placement of the wooden shoe on the foot along with its proper application are essential. It must be stated from the onset, that the application of the wooden shoe must be combined with the appropriate foot trim for the clinician to achieve consistent effective results from this modality. Chronic laminitis is the disease most often treated with the wooden shoe, so its use here will be stressed when describing the overall procedure.


Advantages


The wooden shoe has all the mechanical aspects that can be incorporated in other farriery systems previously described yet it may possess some additional advantages over previous methods. A major advantage of the wooden shoe, coupled with the trim, is its ability to redistribute the load (weight) evenly over a specified section of the foot due to its flat solid construction (O’Grady and Steward 2009; Parks and O’Grady 2009; O’Grady 2010, 2011). Silastic material added to the solar surface of the foot further increases the surface area of the foot enhancing the effects of placing one flat surface against another (Parks and O’Grady 2015). Another advantage is its nontraumatic application that eliminates the necessity to use local anaesthesia in the case of chronic laminitis or other painful foot problems (O’Grady and Steward 2009; Parks and O’Grady 2015). The wooden shoe is constructed from readily accessible materials (wood) or can be purchased commercially.1 Breakover and heel elevation can be fabricated into the shoe and the beveled perimeter of the shoe decreases the torque on the lamellae at breakover by moving the ground reaction force axially. The beveled perimeter of the shoe also appears to concentrate the load (weight) under the distal phalanx due to the solid base of the shoe. Heel elevation, when necessary, can be applied in a uniform manner by altering the shape of the wooden shoe or by attaching a degree pad to the foot surface of the shoe. The shoe can be easily adjusted using radiographic guidelines and the biomechanical or structural requirements of the individual foot conformation.


Mechanism


The wooden shoe addresses three of the principles used in applying therapeutic farriery. The first is to redistribute the load (weight of the horse) or unload the forces on a section of the ground surface of the foot. Secondly, to reposition breakover and lastly, to provide heel elevation when necessary to decrease the tension in the deep digital flexor tendon (DDFT) (O’Grady 2006, 2011; Parks 2011, 2012; Parks and O’Grady 2015). These three principles are especially relevant when treating chronic laminitis. To understand these principles, it is necessary to briefly consider foot biomechanics and the moments about the distal interphalangeal joint (Eliashar 2007; Parks 2011, 2012; Parks and O’Grady 2015). In a standing horse, the weight of the horse borne by the limb exerts a force on the ground which is opposed by an equal and opposite force, the ground reaction force (GRF). The GRF acts on any point of the foot touching the ground. The summation of these forces can be calculated to have a central point of action which is termed the centre of pressure


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