SYMPTOMS 163 



appear iu everj- other respect to be in perfect health. In the 

 older animals — the wethers and breeding ewes — the same 

 glands may be enlarged to a considerable degree reaching the 

 size of a hens egg or even larger. Some of these sheep may 

 show a certain degree of unthriftiness or even emaciation. 

 The disease is found in its most advanced stages in the older 

 ewes, which is probably due to the fact that the wethers are 

 generally disposed of before they are three years old, while a 

 good breeding ewe is frequently retained for seven or eight 

 years. In such old animals the superficial lymphatic glands 

 may be enlarged to such a degree as to interfere with locomo- 

 tion, while the deeper seated glands and those of the body 

 cavities are similarly affected. In the advanced cases the 

 lesions often become disseminated by metastasis to the princi- 

 pal organs of the body. In such cases the disease maj' assume 

 the appearance of chronic broncho-pneumonia or pleuris}-, 

 with occasional cough, slight dyspnoea and increasing emacia- 

 tion and ansemia. The course of the disease is exceedingly 

 slow. For this reason owners of affected flocks are often 

 totally ignorant of the presence of the disease. This fact ren- 

 ders it verj^ difficult to obtain reliable information regarding 

 its prevalence save from the statistics obtained from the 

 slaughter houses. A majorit\' of the inspectors have until 

 recently classified the lesions either as tuberculosis, pyemia or 

 abscesses. In response to inquiries it was found that the ma- 

 I'ority of cases which had been condemned under these head- 

 ings were undoubtedly caseous lymphadenitis. Several 

 thousand cases are annually observed in the slaughter houses 

 of the United States, but only a fraction of these are advanced 

 to a degree that would warrant a total condemnation of the 

 carcasses. Meat inspectors agree that lambs are very rarely 

 affected, and that the progress of the morbid changes in the 

 majority of cases is coordinate with the age of the animal. 



§ 124. Morbid anatomy. The principal lesions are 

 confined, according to the various descriptions, especially that 

 by Norgaard and Mohler, to the lymphatic glands. In many 

 cases only a single gland is affected. The relative frequency 

 with which the various glands become the seat of the lesions 



