404 INFLAMMATION OF STRUCTURES ENCLOSED BY THE HOOF. 



outer cartilage suffers more frequently than the inner. 5. 

 Ossification sometimes occurs at an early age, usually when the 



Fig. 382. — Pedal bone, with almost complete ossification of the lateral cartilages, a, pedal 

 bone ; b, wing of pedal bone, from which point, as a rule, ossification commences ; 

 c, articular surface ; d, rough, uueven surfaces. 



animal is first put to work. 6. Well-bred animals suffer less 

 frequently than others. 7. The use of animals, of heavy build, 

 on hard roads favours the occurrence of side bone. 



The symptoms vary according to whether one or both carti- 

 lages are atiected, and whether ossification is partial or com- 

 plete. Expansion of the hoof is always diminished, and may 

 be entirely suspended. 



The diagnosis of side bone is easy as soon as the upper 

 margin of the cartilage has become ossified ; it then feels hard. 

 On the other hand, when ossification has only attacked the 

 lower portion of the cartilage lying within the hoof, it is either 

 very difficult or absolutely impossible to detect the change, 

 though the form of the hoof sometimes gives valuable indica- 

 tions. 



Side bones produce a clumsy constrained action and at times 

 marked lameness. The symptoms are aggravated by rapid 

 work on hard roads, by allowing the hoofs to become dry, and 

 by using high calkins. When, however, the hoof is kept moist, 

 animals may work for a long time without inconvenience. 



The causes are (1) congenital predisposition, in heavy, coarse- 

 bred horses, and (2) excessive concussion produced by w^ork on 

 hard roads, for which reason the disease is frequent in large 

 towns. The fact that the outer half of the foot suffers the 



