10 PHE horse's foot, 



The bones proper to the foot are three in number, viz.-«-« 

 the coffin bone, the navicular bone, and part of the coronet 

 bone : they are contained within the hoof, and combine to 

 form the coffin joint ;* but the smallest of them, the navicular 

 bone, is of far more importance as connected with our subject 

 of shoeing, than either of the others ; for upon the healthy 

 condition of this bone, and the joint formed between it and the 

 tendon, which passes under it to the coffin bone, and is called 

 the navicular joint, mainly depends the usefulness of the 

 horse to man. 



This small bone,f which in a horse sixteen hands high 

 measures only two and a quarter inches in its longer diameter, 

 three fourths of an inch at the widest part of its shorter 

 diameter, and half an inch in thickness in the centre, its 

 thickest part, has the upper and under surfaces and part of 

 one of the sides overlaid with a thin coating of gristle, and 

 covered by a delicate secreting membrane, very liable upon 

 the slightest injury to become inflamed ; it is unfortunately 

 so placed in the foot as to be continually exposed to danger ; 

 being situated across the hoof, behind the coffin bone, and 

 immediately under the coronet bone ;:]: whereby it is compelled 

 to receive nearly the whole weight of the horse each time 

 that the opposite foot is raised from the ground. 



The coffin bone§ consists of a body and wings ; and is 

 fitted into the hoof, which it closely resembles in form. Ita 

 texture is particularly light and spongy, arising from the 

 quantity of canals or tubes that traverse its substance in 

 every direction, affi^rding to numerous blood-vessels and nerves 

 a safe passage to the sensitive and vascular parts surrounding 

 it ; while the unyielding nature of the bone effectually pro- 

 tects them from compression or injury under every variety 

 of movement of the horse. 



In an unshod foot the front and sides of the coffin bone are 

 deeply furrowed and roughened, to secure the firmer attach- 

 ment of the vascular membranous structui'e, by which the 

 bone is clothed ; but in the bone of a foot that has been fre- 

 quently shod, this appearance is greatly changed, the furiow? 

 and roughness giving place to a comparatively smooth surface 

 This change I imagine to be produced by the shoe limiting 

 if not destroying, the expansive power of that part of the horn 

 to which it is nailed ; whereby a change of structure in the 

 membrane itself, as well as absorption of the attaching por- 



• Page 50, fig. 6. t Page 50, fig. 5. t Page 50, fig. 6. § Page 49, fig. 4 



