SYMPTOMS AND DIAGNOSIS 29 



post-mortem examinations and a discussion of this in- 

 fection is given on p. 37. 



From the descriptions given by different authors, 

 it is probable that many of the symptoms described 

 under the heading of "Scrapy" and "Scrapie" are 

 not caused by Johne's bacillus, but are due to entirely 

 different causes. Indeed, it is unlikely that in an un- 

 complicated case of Johne's disease in a sheep the 

 symptoms are very different from those observed in 

 cattle. The skin lesions probably belong to another 

 condition, and the name " Scrapy " should be reserved 

 for this disease; while "Johne's Disease" should be 

 the name given to the disease of sheep produced by an 

 infection of Johne's bacillus in the gut and mesenteric 

 glands. This view is now held by most workers. 



The present writers observed no symptoms, except 

 some wasting, in five sheep experimentally inoculated 

 with pure cultures of Johne's bacillus isolated from 

 a cow ; but the animals were killed when the disease 

 was in an early stage, and we know that in cattle 

 the disease must be advanced before definite clinical 

 symptoms become manifest. 



In 191 1 we inoculated two young goats with pure 

 cultures of Johne's bacillus. Seven months later the 

 animals were apparent!}^ in good health, except that 

 one of them occasionally showed some slight diarrhoea. 

 No rise of temperature had been noted, their appetites 

 remained normal ; yet on post-mortem examination 

 both were found to be affected with Johne's disease, 

 and showed the typical lesions (pp. 53 and 151). 



In the case described by Lienaux in a horse, diar- 

 rhoea, emaciation, and fever were present ; but as this 

 animal was also suffering from tuberculosis, it is prob- 

 able that the fever, at least, was caused by the tuber- 

 cular lesions. 



