426 DISEASES OF THE HORSE. 



impaired. But when the dropping is sudden and the soft tissues are 

 destroyed, the horn rapidly crumbles away and the toe of the bone 

 comes through. In many of these cases the soft tissues remain 

 uncovered for months. When they are eventually covered it is with 

 a thin, slightly adherent horn that stands but little or no wear. The 

 sole being now convex, the diseased tissues bear unusual weight by 

 coming in contact with the ground, and hence it is that these animals 

 are generally incurable cripples. 



In the majority of cases where the sole is raised to meet the pedal 

 bone and pumiced sole occurs, it is due not to pressure of the bone 

 from within (for the tissues are capable of adapting themselves to the 

 gradual change), but to impaired vitality of the sensitive tissues from 

 the inflammation and to the constant concussion and pressure applied 

 from without during progression. To this is to be added the paring 

 away of the horn by the smith when applying the shoe, thereby keep- 

 ing the sole at this point too thin. 



Turning up of the toe. — In many cases of laminitis which have 

 become chronic it is found that the toe of the foot turns up ; that the 

 heels are longer than natural ; while the hoof near the coronary band 

 is circled with ridges like the horn of a ram. Even in cases where 

 recovery has taken place, and in other diseases than laminitis, these 

 ridges may be found in the wall of the foot. But in such cases the 

 ridges are equally distant from each other all around the foot, while 

 in turning up of the toe the ridges are wide apart at the heels and 

 close together in front, as seen in the figure (Plate XXXIII, fig. 4). 

 These ridges are produced by periods of interference with the growth 

 of horn alternating with periods during which a normal or nearly 

 normal growth takes place. When the toe turns up it is because the 

 coronary band in front produces horn very slowly, while at the heels 

 it grows much faster, causing marked deformitj^ 



Animals so affected always place the abnormally long heel first 

 upon the ground, not alone because the heel is too long, nor as in acute 

 or subacute laminitis to relieve the pain, but for the simple reason that 

 the toe is too short and lifted away from its natural position. To 

 bring the toe to the ground the leg knuckles at the fetlock joint. 



The pain and impairment of function in these cases always result in 

 marked atrophy of the muscles of the forearm and shoulder, and to 

 some extent of the pectorals, while the position of the fore legs 

 advances the shoulder joints so far forward as to cause a sunken 

 appearance of the breast, which the laity recognize as " chest 

 founder." 



The lesions of turning up of the toe are permanent, and are the 

 most interesting pathologically of all the complications of laminitis. 



Treatment. — The treatment of laminitis is probably more varied 



