244 GENERAL THERAPEUTICS FOR VETERINARIANS 



duced by Loffler in 1899, did not answer the purpose. It is doubtful if the 

 sera employed by Nocard and Loffler on cattle (2 to 3 weeks' immunity), 

 sheep and swine (3 to 8 weeks' inmmnity) wiU prove of practical value. A 

 method of protective vaccination suitable for practice ia not yet known. 

 Loffler's serum (1912) is not adapted to general use because of the high price 

 (about $7 per animal), the complicated process (four vaccinations) and the 

 short duration of the effect. 



Sheep Pox. — In the first half of the nineteenth century, entire flocks of 

 sheep were subjected to protective vaccination against sheep pox (ovination) 

 each year, with the assistance of special vaccination institutes, whether an 

 outbreak of the disease was threatened or not. This regulation proved to be 

 very objectionable. Not only did the protective vaccinations estabUsh per- 

 manently infected flocks, in which the disease became stationary, but the 

 infection spread from these flocks to the adjoining regions, the danger of 

 healthy animals being infected by vaccinated individuals being exceedingly 

 great. In several countries, for example in Prussia and Austria, the spread 

 of the disease went hand in hand with the protective vaccination. On the 

 other hand, emergency vaccination is worthy of recommendation, and is 

 therefore included in the requirements of the German sanitary laws (§ 53). 

 Emergency vaccination is employed only in those flocks in which the disease 

 has already broken out. Not only does it cause the disease to run a quicker 

 course, inducing a more rapid extension of the infection through the 

 flock and consequently an earher removal of the sanitary poUce restric- 

 tions, but the disease itself is of a milder type and usually only local, so 

 that frequently there are no deaths and usually not more than 2 per cent, 

 die. Only when all external factors are imfavorable, the losses excep- 

 tionally reach 10 per cent. In addition to emergency vaccination, precau- 

 -tionary or prophylactic vaccination may also be employed when an extensive 

 outbreak of sheep pox prevails in the neighborhood of healthy flocks and the 

 situation is such that there is great danger of these flocks being infected (§ 54). 



The vaccine, or "ovine," can only be obtained from sheep with normally 

 developed pox and in which the disease runs a benign covurse. The lymph 

 must be entirely clear and limpid, neither turbid nor purulent; it is therefore 

 usually collected from the vaccinated sheep on the 10th to the 12th day after 

 the vaccination, or 6 to 8 days after the eruption. The vaccinated sheep must 

 be kept separate from the sheep from which it was inoculated, and the sheep 

 to be vaccinated must not be permitted to come in contact with the infected 

 isheep from which the material for inociflation ia obtained, otherwise infection 

 may take place spontaneously at the same time. The inoculation may be 

 made on the inner surface of the ear, 4 cm. from the tip, or better on the under 

 isurface of the tail, 10 to 12 cm. from the anus. In the latter case the animal 



