ON THE NAVICULAK DISEASE. 49 



ill iiis life leaves his stable in the morning perfectly 

 sound, continues sound the greater part of his 

 journey, and momentarily, without any apparent 

 cause, drops violently lame : the rider as suddenly 

 dismounts, with the impression that his horse has 

 picked up a stone ; takes up his foot, but looks in 

 vain for the stone, or any other cause to account for 

 this visitation ; and many instances will this recall 

 to the reader where horses were never subsequently 

 restored to a sound working condition. 



Such a lameness I conceive to be an actual lesion 

 or rupture of some part of the delicate synovial 

 membrane ; and although there are few opportuni- 

 ties of dissecting these cases of lameness, when re- 

 cent, yet I think I have observed that which will 

 warrant me in stating, that the membrane lining 

 the tendon is more frequently the part first injured 

 than the bone or its synovial covering, the spot 

 being generally within or very near the concavity 

 in the tendon which receives the corresponding con- 

 vexity of the navicular bone. But when the bone 

 or its articular 'cartilage exhibits disease, it is in- 

 variably confined to that portion of the under sur-. 

 face of the navicular bone which is placed nearest 

 the sensible frog, and is most apparent towards the 

 middle of the convex ridge of that bone. 



From the facts that I have collected relative to d is Jas" at 'its"^ 

 groggy lameness, 1 am thoroughly convmced we admiuii.s of an 

 have as much control over the early stage of this tain cun/' 



E 



