STATE HYGIENE 505 



root of the tail, and dealt with by immediate amputation 

 above the seat of inoculation. All this belongs to the realm 

 of pathology. The point is mentioned here as the question 

 is one of importance to the hygienist. Inoculated animals 

 after about the fourth or fifth day should be inspected 

 morning and evening, and the least sign of carrying the tail 

 away from the body indicates all is not going right, and 

 demands immediate attention. 



The greater the local reaction, within reasonable limits, 

 the greater the amount of protection ; where there is no 

 reaction in a susceptible animal there is no immunity. A 

 local reaction the size of a hen's egg is sufficient. 



There are some who consider one inoculation gives per- 

 manent immunity, but it is not so. Theiler places the 

 duration of immunity at probably one year; it does not begin 

 until towards the end of the reaction, and animals exposed 

 to infection before this time contract the disease in spite of 

 inoculation. Inoculation shortens the incubation period. 



Inoculation has this value, that by its means we can 

 check the disease, and the losses from the operation are 

 very small provided ordinary care be adopted. 



Pleuro-pneumonia is a very insidious aifection ; it has a 

 long incubative period, probably not less than three weeks 

 or a month, and it would be wise not to declare a herd 

 free until two months after the last case. Again, we must 

 impress the danger of old, so-called encysted, lung cases ; 

 these are capable of infecting fresh and unprotected cattle, 

 and in the days when cows were allowed to be treated in 

 the United Kingdom, these encysted cases were, perhaps, the 

 most common means of keeping the disease alive. 



LEGISLATION. 



The Diseases of Animals Act, 1894, and the Pleuro-Pneumonia 

 Order of 1895. 



The regulations regarding notification, the action of the police, of 

 the Inspector, movements of cattle into or out of an infected place, 

 removal of manure and other things, are practically the same as in 

 Cattle Plague. 



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