THE SHOE AND THE FKOG. 325 



comes the indiarubber-like " frog," occupying the centre 

 of the hoof, and being exactly analogous to the footpads 

 of a dog or cat. To remove or lessen the frog, so as to 

 throw all the weight on the crust, is like cutting away 

 the foot-pads of the dog and making it walk on the tips 

 of its claws. 



The remarkable structure called the " external frog " 

 is also meant for perpetually wearing away and renewal. 

 It is not rubbed off like the horn of the crust, nor flaked 

 off like that of the sole, but drops off in ragged flaps 

 which need no touch of the farrier's knife, and will not 

 produce thrush or any other ailment if suffered to remain 

 until they fall of their own accord. 



Now, if the hoof be protected from friction, as is the 

 case when shoes are added, it is evident that the horn 

 must be artificially removed. The use of the knife is 

 therefore a necessity, as far as removing the crust goes, 

 and even in Japan, where the shoes are tied and not 

 nailed to the hoof, the crust has to be pared, just as 

 those who do no hard manual work are obliged to pare 

 their nails. It is also evident that as the hoof grows 

 unequally it must be trimmed unequally, and more 

 material must be removed where it grows fastest. 



Secondly, as the hoof is elastic, it is evident that it 

 ought not to be confined by a rigid and non-elastic shoe ; 

 and lastly, as in the untouched hoof the weight of the 

 animal is thrown on the central " frog," toward which the 

 various elastic structures converge, the shod hoof ought 

 to allow of the same central bearing. 



