**6. Conclusions**

*Veterinary Anatomy and Physiology*

the condition, with 5 being the worst outcome [77].

foot lameness in the ipsilateral front limb.

shape of the hoof [83, 84].

time requirement for healing, if healing is possible [71]. In dairy cows it represents the most important financial and welfare problem faced by the industry [60], as it is responsible for a drop in reproductive efficacy, a decrease in milk production, and increased culling rates [5, 69]. Similarly, in horses, foot lameness is a significant and predominant medical disorder which accounts for about to \$1 billion in losses annually for the equine industry in the United States of America [72, 73]. In the UK, the maintenance of each horse is estimated to cost about £2660 annually and much of this in the treatment of foot lameness [74]. Foot lameness in the horse is the most prevalent and frequent medical issue, affecting about 11% of the general equine population in the UK in 2011 [75]. This rose significantly in 2012 to 18.6% [76] and was thought to be due to factors such as differing foot balance, shoeing and trimming techniques. Some subpopulations however, seem to be more affected than others as, for example, it is estimated that nearly 33% of dressage horses in the UK suffer from foot lameness [69]. The clinical diagnosis of foot lameness in the equine population is subdivided into scores ranging from 0 to 5 depending on the degree of

Lame horses adapt their gait to compensate for the pain originating from damaged tissues or foot lesions [78–80]. Accordingly, foot lameness is considered to be one of the most common signs of kinetic disorder affecting the musculoskeletal system [30]. As forelimb foot lameness is more common than hind limb foot lameness [81], it has been suggested that conformations of the distal limbs may have a substantial impact in the development of front and rear limb foot lameness [66]. The relatively high prevalence of forelimb foot lameness [81] which reaches to more than 75% of equine foot lameness being found in a forelimb particularly in breeds such as Thoroughbred horses and 40% in Standardbred racehorses [82]. This may be explained by that fact that the centre of gravity of the horse is closer to the front limbs than the rear limbs, as the loading ratio is spread approximately 60% forelimbs: 40% hind limbs [66]. Other research [80] has shown that horses with severe foot lameness in the front limb display an untrue foot lameness in the contralateral rear limb, whereas horses with a real rear limb foot lameness exhibit an incorrect

Although the aetiology of equine foot lameness is still an active research area, recent efforts have also tried to determine whether the hoof shape is a disposing factor for foot lameness-causing lesions. The investigation of variations between foot lameness and non-foot lameness affected horses [51], demonstrated that the angle between the capsular wall and the ground is larger in the lame horse with an enlarged heel, curved or misshapen coronary band, that diverging growth lines can occur, and that the tubular horns differ from non-lame horses. It was suggested that hereditary influences and trimming are factors contributing to the asymmetrical

In chronic foot lameness, the hoof capsule of the lame foot can be more distorted than in the non-lame one [85], as a result of altered loading forces applied to the hoof, hence affecting the shape of the hoof and the internal structures of the foot [86, 87]. These variations in the shape of the capsule are triggered by biological sources causing autolysis of the collagen fibres connecting the epithelium to the bone [68]. The role of these fibres is to support and suspend the weight of the horse via the distal phalanx, as well as to maintain the shape of the capsule constant [88, 89]. Another cause that could lead to hoof distortion is the ability of the foot to produce keratinous material proximally [90]. A number of chronic foot lameness states can be related to sheared heels causing palmar foot pain and hoof deviation [34]. Sheared heels are considered as one of the main causes of foot lameness in the equine genus, which results from an abnormal stride and persistent uneven weight bearing [91]. This leads to higher soft tissue strains that predispose the hoof capsule to deformation [92].

**28**

There is no doubt that understanding the anatomy, histology and physiology of the equine foot and limb is essential in treating a wide range of disorders. Advances in technology such as magnetic resonance imaging, computed tomography and other imaging techniques also play a role in assisting both anatomical knowledge and understanding equine conditions [99]. Coupled with more traditional techniques recent research has used these techniques to show bone conformation and growth, vascularisation and a number of other factors which could help inform us about anatomy and limb disorders. Although much is known about equine anatomy and histology, more is being discovered in both the normal and pathologically affected horse. In addition, new information from cellular and molecular studies is advancing not only the anatomical and histological sides but also the physiology and function of the equine limbs and the disorders they are prone to.
