234 THEORY AND PRACTICE 



bones are usually shortened, thickened, rarified, curved, and 

 twisted. The rari'ned condition is most frequently seen in the 

 epiphyseal ends of the long bones, which become considerably 

 enlarged. 



This disease is not infrequently congenital, and seems at 

 times to be hereditary. Bad hygiene, malnutrition, and certain 

 inflammatory diseases seem to be exciting causes. In the con- 

 genital form the causes mentioned probably operate upon the 

 young through the mother. The disease usually manifests itself 

 in the first and second year of life. In cases that live beyond 

 puberty the disease recovers but the deformities persist. Den- 

 tition is irregular and delayed. The animal, however, may be 

 well up to two to six years and then be affected. It is com- 

 mon in puppies that are fed on starchy food. Foals, too, are 

 apt to have it. 



The first intimation of the disease is a peculiar lassitude and 

 the play is not so lively; the long bones of the legs begin to bow, 

 especially in the front legs, the convexity being outward. The 

 femur is usually curved anteriorly as well as externally. 



At the articular ends of the bones, where the diaphysis joins 

 the epiphysis, instead of a narrow distinct white line, one finds 

 an enlargement consisting of porous, irregularly formed bone 

 in which there is a widely separated plexiform or fibrillar ar- 

 rangement of osteoid substance deficient in lime-salts. These 

 areas alternate with others of irregular ossification. The mar- 

 row is much like that found in the fetus. Next to the growing 

 cartilage of the epiphysis is a zone of osteoid tissue in which 

 the bony partitions inclose patches of cartilage. • 



The irregular growth and rarefaction of the bones give them 

 a pronounced predisposition toward bending and fracture, es- 

 pecially of the green-stick variety, while the continued pressure 

 produced by the weight of the body results in permanent de- 

 formities. 



Treatment. — There should be a complete change of food. 

 In the foal, wean him and feed on cow's milk liberally, say a 

 gallon three times a day, and more as he grows older. Skim 

 milk even if it is sour is better than fresh milk, because it con- 

 tains less fatty matter ; in addition give bone dust, oatmeal, etc.. 



