ORGANS OF LOCOMOTION 233 



enlargement of bones or deformity, and unfavorable in those cases 

 showing deformity. 



Treatment. — Provide sanitary surroundings and proper food, cor- 

 rect digestive disturbances and administer lime salts in the feed or 

 M'ater. 



PURULENT OSTEOMYELITIS 



Inflammation of the bone marrow occurs in swine. This condition 

 is sporadic, and is most frequently observed in young animals. 



Etiology. — Purulent osteomyelitis is caused by infection. Vari- 

 ous pyogenic microorganisms have been identified, such as Staphylo- 

 coccus pyogenes aureus and albus. Streptococcus, and in one instance 

 the Bacillus pyocyaneus, was isolated and apparently occurred in 

 pure culture. There is probably some predisposing cause, such as 

 hog cholera, but all of the cases observed have shown no lesions of 

 cholera or other than the primary disease. 



Lesions. — The ribs are most frequently affected. The bone mar- 

 row becomes hyperemic and invaded with leukocytes and inflam- 

 matory products, and the internal pressure causes the bone to be- 

 come enlarged and the marrow cavity to be increased in size. The 

 marrow and the inflammatory exudate disintegrate and form pus. 

 As pus is produced the bone becomes larger and round, although it 

 may show some irregularities in shape. The pus in the marrow 

 cavity may erode the bone tissue and discharge, thus producing a 

 fistulous tract, but more frequently the pus becomes caseous and may 

 later undergo calcification. Suppurative processes are rarely observed 

 in other bones. 



Symptoms. — There is little outward manifestation of purulent 

 osteomyelitis other than the formation of a barrel chest (the ribs 

 form a wider arch, the thorax appearing almost round in cross-sec- 

 tion), and the prominent tumefied ribs. If the affected animal is 

 in good condition the ribs are not visible. These cases are usually 

 of long standing, and the disease is essentially chronic. Antemortem 

 diagnosis is rarely made. Purulent osteomyelitis can be distinguished 

 from osteomalacia by the localization of the process in the ribs. 



Treatment. — Medicinal treatment is of no value. 



TRICHINOSIS 



Trichinosis assumes two forms, intestinal and muscular. Both 

 types occur in the same animal, the intestinal preceding the mus- 

 cular form. 



