206 THE HORSE. 



these structures are full of blood-vessels, for not only are the 

 arteries above described ramifying thus extensively upon them, 

 but the blood is returned by corresponding veins. 



Besides the pedal and navicular bones, there are also 

 two cartilaginous plates at the back of each ala of the pedal bone, 

 which are of considerable importance. These have been called by 

 the late Professor Coleman the lateral and inferior cartilages, 

 whilst others have given them the name of the true and false. 

 The lateral cartilages extend backwards and outwards from the 

 posterior and upper borders of the coffin or pedal bone. They are 

 united in front with the expanded terminations of the extensor 

 tendon, and by cellular membrane with the lower end of the os 

 coronae. Posteriorly they wind upwards around the ala of the 

 pedal bone, to which they are firmly fixed, forming the foundation 

 for the heel. But in addition to these lateral or true cartilages, 

 there are also two others, of a fibro-cartilaginous nature, which 

 commence from the sides of the former and proceed forwards 

 towards the heels of the pedal bone, and spread inwards upon the 

 surfice of the tendo-perforans. They are scarcely worthy of being 

 described as distinct cartilages, and appear more like ordinary 

 condensed cellular membrane. 



It will thus be seen that the foot of the horse is a most compli- 

 cated structure, which is liable to derangement whenever the hoof 

 or horny ease is interfered with, and this may occur either from 

 mismanagement in shoeing, causing mechanical injury, or from 

 inflammation of the secreting surface, which will end in the for- 

 mation of imperfect horn, or from punctures or other wounds of 

 the foot. Perhaps in no organ does an injury so soon produce a 

 return at compound interest, for the inevitable first result is a mal- 

 formation of the hoof, and this again only adds to the original 

 mischief. Hence it is that in the foot, more than in any other 

 pare even, prevention is better than cure, for in many of its 

 diseases it happens that a cure cannot be obtained without rest ; 

 and yet it is also the fact that the secretion of horn will not go on 

 perfectly without the stimulus of necessity afforded by exercise. 

 The position of the leg is such that its veins have a hard task to 

 perform at all times in returning the blood from the feet, but when 

 the horse is not exercised at all they become doubly sluggish, and 

 congestion in them is almost sure to occur. 



