1 62 OVINE CASEOUS LYMPH-ADENITIS 



§121. Geographical distribution. In the United States 

 this disease is quite common in certain districts in the western 

 and southwestern states. It exists in South America, Aus- 

 tralia and Europe. 



Sivori found that lo per cent of the old sheep killed in 

 Buenos A^'res were affected. The prevalence of the disease in 

 the United States, as indicated b}' the reports of the federal 

 meat inspectors, show that of 16,000,000 sheep slaughtered in 

 Chicago, Kansas Cit}' and South Omaha 3,236 were con- 

 demned for caseous lymph adenitis or lesions which might be 

 confounded with it. It is reported by an inspector from Los 

 Angeles that of 950 sheep coming from an infected district, 82 

 were suffering from lymph adenitis. 



§122. Etiology. Caseous lymph aden- 

 itis is caused by a specific organism. It ap- 

 pears to be the one described first by Preisz 

 as the bacillus of pseudo-tuberculosis. Its 

 description shows it to vary in size to such 

 a degree that its polymorphism is said to be 

 characteristic. It is nonmotile and hence be- 

 longs to the genus Baderinm. It is aerobic, 

 facultative anaerobic, it stains readily and does not produce 

 spores. It develops readily on agar when this medium is inocu- 

 lated from the caseous material from the affected glands. It 

 is pathogenic for mice, guinea pigs and rabbits. 



§ 123. Symptoms. In the majority of cases no symp- 

 toms of any importance are observed in the affected animals 

 during life. The course of the disease is that of a chronic 

 affection and the pathological changes develop so slowly that 

 no general or local interference with the health of the affected 

 animals are observed, in lambs and sheep that are bred and 

 raised for mutton, and which are marketed before they are 

 two years old. Only in breeding ewes and wethers does the 

 disease advance to a degree which makes it clinicalh' recog- 

 nizable without the aid of manipulation. The affected ani- 

 mals upon examination show an enlargement of one or more 

 of the superficial glands, the precrural and the sub-scapular 

 glands being most often involved. The animals thus affected 



