definition and symptoms of navicular disease. 407 



10. Naviculak Disease 



is a chronic inflammation of the lower surface of the navicular 

 bone and the portion of flexor perforans tendon passing below 

 it. 



The disease consists essentially in cluiDge in the gliding 

 surface of the navicular bone and of the cartilage covering it. 

 The previously smooth surface of the bone becomes roughened, 

 the tendon abraded, inflammation then increases, the portions 



Fig. 385. — Preparation illustrating navicular disease. 1, os pedis; 2, flexor pedis perforans 

 tendon drawn downwards; 3, lower (gliding) surfitce of the navicular bone; 4, coronet 

 bone ; a and b, roughened, abraded spots on the flexor perforans tendon; c, eroded spots 

 on the navicular bone ; d, proliferations from periosteum on the upper margin of the os 

 pedis. 



of the tendon involved may, in extreme cases, become necrotic, 

 and still further aggravate the existing mischief; finally, 

 periostitis and rarefying ostitis set in, and deposits form 

 around the margins of the bone. 



Occurre7ice. — The lameness usually affects one or both of the 

 fore-feet. Horses with very concave soles appear more subject 



