Tuberculosis in Line Slock. 
7 
Fig. 3.—A modern sanitary bam. Note ventilators and liberal window space. 
HOW THE DISEASE SPREADS IN A HERD. 
The tuberculous cow is the greatest source of 
danger to healthy cattle. Any reacting cattle not 
promptly removed from the herd constitute a source 
of constant infection. 
Tuberculous cattle, sooner or later, begin to give 
off the germs of the disease. These germs escape 
by the mouth, nose, and bowels, in the milk, and 
other discharges. The discharged germs are car¬ 
ried in the air for a time until they fall to the ground. 
Animals in adjoining stalls may take in the germs 
in the feed they eat and thus contract the disease. 
Continuous water troughs in barns containing dis¬ 
eased cattle are a source of danger. Drinking 
holes containing material from infected animals are 
likewise dangerous. 
Failure to clean and disinfect the premises occu¬ 
pied by the diseased cattle constitutes another 
source of danger. Infected milking tubes and the 
practice of feeding calves with raw milk from tuber¬ 
culous cows are other means by which tuberculosis 
spreads in a herd. 
