OVINE CASEOUS LYMPH-ADENITIS 209 
OVINE CASEOUS LYMPH-ADENITIS (PSEUDO-TUBERCULOSIS IN SHEEP) 
Synonyms. Pseudo-tuberculosis of sheep; caseous lymph adenitis; 
cheesy broncho-pneumonia. 
Characterization. Caseous lymph-adenitis is a disease of adult 
sheep which until recently was designated as pseudo-tuberculosis. It 
has been characterized by an enlargement of one or more lymphatic 
glands, which contain foci of a greenish-yellow, caseous or purulent 
substance. It is rarely found in young animals. The mortality is 
very low, due perhaps to the fact that the sheep are slaughtered before 
the disease runs its course. It does not occur in epizodtic form al- 
though it is more prevalent in certain localities than in others. 
History. The name “ovine caseous lymph-adenitis” was proposed 
by Norgaard and Mohler in 1899. These writers found the lesions 
and the accompanying microédrganism to correspond with those 
described by Preisz and Guinard in 1891 as pseudo-tuberculosis. 
The bacterium was fully described by Preisz in 1894. It appears that 
at least many of the cases of lymphatic gland enlargement in sheep 
heretofore called pseudo-tuberculosis belong to this disease. Gilruth 
prefers the name pseudo-tuberculosis. Cherry and Bull describe it as 
caseous lymphatic glands and Sivori as caseous broncho-pneumonia, 
the bacterium of Preisz being found as the probable cause in each case. 
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, New Zealand, Australia and 
Europe. 
Sivori found that 10 per cent. of the old sheep killed in Buenos 
Ayres were affected. The prevalence of the disease in the United 
States is indicated by the reports of the federal meat inspectors, 
which show that of 16,000,000 sheep slaughtered in Chicago, Kansas 
City and South Omaha 3,236 were condemned 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 a 
certain district, 82 were suffering from lymph-adenitis. 
Etiology. Caseous lymph-adenitis is caused by a specific micro- 
organism first described by Preisz as the bacillus of pseudo-tubercu- 
losis. Its description shows it to vary in size to such a degree that its 
polymorphism is said to be characteristic. It is non-motile and hence 
belongs to the genus Bacterium. It is aérobic, facultative anaérobic, 
