NAVICULAR DISEASE. 



205 



fore feet are afiected. The lameness may, after a rest, disappear 

 for the time being: : but only to return on the resumption of worls. 



The CAUSE of this disease appears to be unknown. 



The TREATMENT is similar to that of "seedy-toe." The 

 affected liorn at the coronet should be kept closely pared down. 

 I'arathn nil is a cood dressing. 



Fig. 66. — Inflammation of the perioplic ring. 



Navicular Disease. 



NATURE AND PROGRESS.— This disease (Pigs. 67, 68 and 69) probably 

 begins as inflammation of the navicular bone, or of the cartilage upon its 

 lower surface. The chronic inflammation set up in the bone produces 

 changes in the substance of the bone, somewhat similar to those of 

 osteoporosis ; in fact, we have " rarefying ostitis," in which the affected 

 portion of compact bone is slightly redder than natural ; the openings of 

 the Haversian canals after a time become somewhat increased in size, and 

 consequently a larger number are visible to the naked eye. As the process 



