lo Feb., 19 1 2.] Diseases of Farm Animals. 87 



in the chapter on Prevention of Disease. Lands upon which anthrax 

 has become "enzootic," i.e., where the soil is impregnated with the bacilli 

 and the disease breaks out periodically, should if possible be turned from 

 grazing use for a time and cultivated. The underdraining of low-lying, 

 damp land is also to be recommended, not only because of the removal 

 of stagnating moisture but also because of the soil aeration which draining 

 effects. Under the slow influence of oxygen, anthrax bacilli are gradually 

 robbed of their virulence. Seeing that anthrax is not usually conveyed 

 from animal to animal by direct contact but is most often contracted from 

 the pasture or food, a practical measure towards the prevention of its 

 spread is the removal of all apparently healthy animals from the paddock 

 in which the disease has been occurring to dry upland country. The 

 mortality will almost at once cease, and even if an odd animal does 

 succumb after removal the risk of contaminating the new paddock will be 

 small if the precautions previously mentioned, as to disinfection and the 

 non-opening of the carcase before iburning or deep burial, are strictly 

 observed. Besides, the anthrax germs are not likely to become perman- 

 ently fixed on dry sandy soils. 



Preventive Inoculation. — Immunization of flocks and herds by 

 inoculation with an " anthrax vaccine " has been practised for many years 

 with varying degrees of success. Some of the " vaccines " used consist 

 of an attenuated or weakened culture of the bacillus and others of sterilized 

 anthrax toxins. They are prepared in various ways — {a) by the action of 

 heat (Toussaint), sunlight (Arloing), compressed oxygen (Chauveau) or 

 antiseptics (Chamberlain and Roux) ; {b) by the cultivation of the bacillus 

 in an oxygen atmosphere (Pasteur) ; and {c) by sterilizing anthrax blood 

 and dissolving out the soluble toxins (Law). 



Pasteur's method is the one that has given the best results and by it 

 protective virus of two grades of virulence are usually used. The first 

 is a very weak virus (" ist vaccin ") resulting from cultivation in oxygen 

 at a high temperature (42 degrees C), to prevent the formation of spores 

 for twenty- four days. The second or stronger virus (" 2nd vaccin ") is 

 got when cultivation under the same conditions is carried on for twelve 

 days. To inoculate, the prescribed dose of ist vaccin is injected under 

 the skin on the innei aspect of the thigh (sheep) or behind the shoulder 

 (cattle) and fourteen days later the 2nd vaccin is similarly injected. The 

 dose must be regulated according to size and age, but the average is Jth 

 of a cubic centimeter for sheep and double that amount (Jth c.c.) for 

 cattle. The protection lasts for about a year or more, after which re- 

 inoculation is necessary. 



It cannot be confidently recommended to practise inoculation for anthrax 

 indiscriminately It should never be practised except on anthrax lands, 

 that is,, where the disease occurs periodically as an enzootic, as " elsewhere 

 it may lead to the stocking of a new area with a malignant germ (the anthrax 

 bacillus) which in young and susceptible animals re-acquires its original 

 virulence." Another drawback as regards sheep is that different breeds 

 and families appear to possess a \ery irregular sensitiveness to the same 

 virus ; hence in large part doubtless, the many fatalities that result from 

 inoculation of sheep on the one hand and the many failures to protect on 

 the other. In Australia the best results are obtained between May and 

 September. 



Law's method of anthrax protection by injection of sterile solution of 

 anthrax toxins has been practised with success m America. The blood 



