DISEASES OF CATTLE 251 



Cleanliness. Since the manure of tuberculous cattle often con- 

 tains living tubercle germs in vast numbers, the importance of keep- 

 ing it well cleaned out of the stable is readily seen. Such manure is 

 not only dangerous to other cattle in the stable, but may be the means 

 of conveying the disease to children. Often cows are seen with their 

 flanks incrusted with dry dung. Parts often break off while the cow 

 is milked, and some of it is likely to fall into the milk pail. The 

 larger lumps are strained out, but the smaller particles remain, and 

 also the tubercle germs, which are small enough to pass through any 

 strainer. These stay in the milk and make it a fruitful cause of the 

 disease in the young. 



Stables should be cleaned out often and the manure put where it 

 can not be picked over by hogs or cattle. These animals are easily 

 infected in that way. Cleanliness also includes keeping the walls 

 and ceilings free from dirt, dust, and cobwebs. These are all good 

 resting places for disease germs. 



Whitewashing the interior of the stable at least twice a year is a 

 great aid to cleanliness, and also has a distinct effect in destroying 

 disease germs. In many municipalities dairy stables are required to 

 be whitewashed at regular intervals, and it is a practice that should 

 be universal. 



VACCINATION OF CATTLE AGAINST TUBERCULOSIS. 



The heavy annual losses which are caused by the ravages of tu- 

 berculosis among domesticated animals have been appreciated by the 

 inhabitants of infected countries for many years. Owing to this 

 realization of the extent of the havoc wrought by this insidious dis- 

 ease, earnest thought and study have been devoted by scientific forces 

 in all civilized countries to the question of its eradication. 



It was known from the first that the fight against tuberculosis 

 among cattle would be a prolonged one because of the hidden manner 

 in which the disease makes its attack, but when the suggestion was 

 made that cattle might be safely and completely immunized against 

 the disease the advantages which might arise from this method of 

 procedure became at once apparent. It is obvious that if the young 

 animals of an infected herd or locality can be thoroughly protected 

 from tubercular infection the root of the matter has been reached, and 

 it is then only a question of time when all the remaining animals can 

 be disposed of and the premises can be cleaned and disinfected and 

 kept free from tuberculosis. 



An appreciation of the advantages accruing from immunization 

 in our tuberculous herds led the Bureau of Animal Industry to in- 

 augurate the tests here recorded. It was clearly seen that it was most 

 desirable to devise some method whereby cattle could be immunized 

 rapidly and without danger to themselves or their attendants. There- 

 fore a number of the most promising methods of applying the im- 

 munizing agent have been tried, and while none of them have proved 

 perfect, some have been more or less efficacious in enhancing the pow- 

 ers of resistance of the animals treated. 



