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LAMTSITIB. 557 



Ptfvtio fovrn continuoa long enough, the pathological changes ara 

 the same also. 



Poilwlogy. — Inflatnmation of the sensitive foot, including 

 Iftinince, sole, and os pedi<». The exudation is greatest at the 

 loo, the foot being most vascular at this point. The pain of 

 larainitjs is most agonising and persistent, because the sensitive 

 foot is invested with an unyielding horny box pressing upon the 

 onijorged blood-vessels, preventing free exudation and swelling, 

 and thus proving a barrier to the method by which congested 

 blood-vessels are relieved. The exudate iu laminitis is found 

 to limit itself to the external surfaces of the sensitive laminre, 

 but in that form caused by violent concuGsion, and which with 

 propriety might be termed " peditis," the exudation may be 

 subperiosteal, detaching the periosteum from the pedal bone 

 by the outpouring of an unhealthy, broken-down, dirty reddish 

 .Coloured fluid ; whilst tlie interstices of the bone, its canals, and 

 lacunre are filled with the some material, forming a barrier to the 

 free circulation of tlie blood, and thus assist in hastening the 

 pToce8«i of necrosis and sloughing. 



Mere laminitis may pass off -without causing structural 

 oliange ; there is but a slight exudate, and this is soon absorbed 

 after the subsidence of tlie inflammatory action. In some 

 cases the lemoval of the exudate leaves a space between the 

 sensitive and horny laminae, Avhidi has led some observers to 

 t^iink that the disease consists essentially of absorption of the 

 bond of union between the two sets of laminae, the formation 

 of a cavity, and the subsequent filling up of it with imperfect 

 cheesy or seedy horn. 



Should the inflammation persist, the exudate accumulates at 

 the toe, increases in thickness,* presses upon the toe of the os 

 pedis in the one direction, and upon the crust iu the other, 

 separating the two, forcing the toe of the bone downwards, and, 

 later on, the toe of the crust upwards. The effect of this change 

 in the position of the bone is the formation of a convex sole. 

 The sole, being pressed upon by the point of the bone, is forced 

 i3ov/nward3, losing its natural concave shape ; whilst from the 

 'BBcretory powers of the sensitive sole becoming interfered with, 

 ■partly arrested or perverted, the horny sole remains thin, weak, 

 cheesy, or spongy, like macerated horn, or even grumous, afford- 

 ing but little protection to the cencitive parts within. The outer 

 liom of the wall, namely, that secreted bj the coronary band 



