H2 VETERINARY LECTURES 



quarters ; but they are very rarely found in flat-footed horses, hacks, 

 or carriage-horses. The principal causes are hereditary predisposi- 

 tion, injuries of various kinds, overreaches, chafing against the 

 sharp edge of a lea-furrow, etc. ; but, in my opinion, the greatest 

 evil of all is the use of high-heeled shoes, removing the frog from 

 its ground pressure, thus throwing the weight on the lateral carti- 

 lages. Above the horny or insensitive frog there are elastic fibres 

 running from the inside of one lateral cartilage to the inside of the 

 other, forming what is called the fatty or sensitive frog, into which is 

 inserted the frogstay, or elevation corresponding to the cleft in the 

 middle of the ground surface of the frog. Now, when the weight 

 of a horse is thrown on its foot, the pastern descends, the lateral 

 cartilages yield and bend outwards at the top of the hoof, about the 

 middle of the cartilage, whilst the top of the cartilage bends over 

 and inwards, acting like a spring, letting the weight of the limb 

 gently down on to the fatty frog, which, in turn, presses on the in- 

 sensitive horny frog, bringing it in contact with the ground, and thus 

 preventing concussion. But when a horse is shod with high or 

 turned-up heels the horny frog becomes displaced, as it were, and 

 thrown out of work, and all the weight is put on to the lateral carti- 

 lages, which, in time, through having all their own work, as well as 

 that of the frog, to do, become ossified, and form side-bones (once 

 side-bones, always side-bones), and this process may go on without 

 any inconvenience or lameness. Shoeing-smiths — particularly 

 those in the country — have the very great fault of cutting away 

 the sides of the horny frog, yet it ought never to be touched. When 

 side-bones cause lameness, remove the shoe, and apply cold water 

 poultices until the inflammation and pain has abated, then ease the 

 shoe or substitute a bar shoe (Plate XV., No. 5) ; this removes the 

 pressure from the quarters, and throws weight on the frog. In a 

 great proportion of cases no lameness is observed, and although 

 the animals step short, yet they can do their work with little 

 or no inconvenience ; nevertheless, they are always considered as 

 unsound. One or both sides of the foot may be affected with 

 side-bone. When they are very large, and cause much lame- 

 ness, the hoof is cut through, with a special saw, at the quarter, 



