54 DISEASES OF SHEEP. ; 



result only obtained. There is still another or third class 

 of vaccination — " preventive vaccination" — which consists 

 in the continual yearly vaccination of the grown-up stock, 

 or animals born since the last regular vaccination of the 

 herd. Such a preventive vaccination of course offers great 

 advantages over the so-called "vaccination in distress" 

 and " precautionary vaccination," allowing the free choice 

 of proper season and of other favorable circumstances, and 

 causing only an inconsiderable loss. In many countries, 

 especially in Austria, such a preventive vaccination is 

 generally in use: the grown-up lambs are regularly vac- 

 cinated in the spring, when such lambs are from three to 

 four months old, the general result being a very consider- 

 able diminution of the former devastations caused by this 

 plague. There are, however, certain parts or countries 

 where the recurrence of pox only happens in very distant 

 periods, say in ten or twelve years, and even more seldom; 

 and on account of the short duration of the life of sheep 

 no danger may exist during several generations ; so that 

 , preventive vaccination is not required and is unnecessary. 

 Such preventive vaccination is therefore only to be recom- 

 mended for particular localities and under particular cir- 

 cumstances ; that is to say, for those localities in which 

 sheep pox is known to recur after short intermissions. A 

 timely and properly executed "precautionary vaccination" 

 is in most cases sufficient to prevent losses from infection. 



The selection of vaccine-matter is of the greatest import- 

 ance, inasmuch as only by means of proper vaccine-matter 

 a reliable prevention of a vehement or malignant disease 

 can be effected. All parts of an animal afflicted with pox, 

 especially the dung, urine and other discharges, the blood 

 and other humors or fluids, are contagious, but probably 

 only during certain periods of the disease. It is therefore 

 necessary to establish certain rules for the selection of the 



