NAVICULAR DISEASE. 333 



sionally begins in the bursa or tendon, probably as a result 

 of direct injury to the parts. The disease is a very 

 common one, especially amongst certain classes of horses; 

 however, it is probable that other and very different con- 

 ditions are frequently mistaken for navicular disease, hence 

 it is not quite so common as some may suppose it to be. It 

 is not at all uncommon to hear of cases of navicular disease in 

 which quick and permanent cures were made : it may be 

 well to state that when navicular disease once becomes well- 

 established, a permanent cure can never be effected, and in 

 cases w^here the so-called quick cures took place, the 

 chances are that such were not cases of navicular disease. 



Pathology. — The cause having operated, inflammation 

 becomes established in connection with the cancellated 

 structure of the navicular bone. The inflammatory process 

 gradually extends to and involves the articular cartilage, 

 which undergoes destruction, by ulcerative absorption ; the 

 tendon becomes involved more or less, inflammation occur- 

 ring in connection with it, and generally adhesions take 

 place. The disease is always confined to the inferior sur- 

 face of the navicular bone, and in connection with the tendon, 

 there being no record of a case ever having been discovered 

 in which the superior surface of the navicular bone had 

 been ulcerated ; the bursa also undergoes destruction, and 

 lameness becomes established. The progress of the disease, 

 as described above, is sometimes very rapid, in other cases 

 its progress is slow, and may extend over a period of several 

 months, or even years. 



Causes.— T\\Q great exciting cause of navicular disease is 

 hard and fast work, particularly on hard roads. An heredi 

 tary tendency may also be mentioned as a predisposing 

 cause, apart from vices of conformation. Individual animals, 

 as well as certain breeds of horses, are more or less subject 

 to navicular disease, on account of faulty conformation, 



