CHAPTER II 



ECONOMIC IMPORTANCE AND ETIOLOGY 



Economic Importance.— Until Johne's disease has for 

 some time been scheduled under the Contagious 

 Diseases of Animals Act, it will be difficult to estimate, 

 with any degree of accuracy, the number of cattle 

 affected with this disease. It may be granted that any 

 animal which shows clinical symptoms is a source of 

 loss to the owner; but an animal may become poor 

 in condition and generally unthrifty from Johne's 

 disease, though it may be killed before the onset of 

 acute diarrhoea. The condition is not as yet generally 

 recognized by stockowners and farmers. Among the 

 smaller men especially, the "scanter" or "waster" is 

 sold at a low price to a butcher or dealer, and in the 

 latter case passed on to spread infection at the next 

 market. 



Harvey, of St. Columb, who has had many years' 

 experience both of small farmers and of cattle breeding, 

 points out the danger of the custom of selling a 

 "scanter" with three or four sound bullocks, and 

 suggests that the sale of an animal known to be 

 affected should be made a punishable offence. This 

 cannot be, however, until a test with a specific diag- 

 nostic vaccine has been recognized, and State legis- 

 lation adopted. 



In the milking breeds, Johne's disease is certainly 



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