Annual Report for IDli of Roi/al Veterinary Colle(je. 269 



from bad to worse when once the stage of emaciation and 

 diarrhoea has been reached. 



There is no doubt that as a rule the treatment described 

 above has beneficial effects, since it arrests the diarrhoea and 

 loss of condition, and markedly prolongs the animal's life. 

 Sometimes, as in Cases I. and II., it may even appear to have 

 effected a complete cure. It must, however, be admitted that 

 in some cases the treatment appears to be without any influence 

 on the course of the disease, and that in the majority of cases 

 it merely prolongs life without enabling the animal to recover 

 its lost condition to any important extent. 



When all the facts are taken into consideration, one cannot 

 advise that treatment of animals at an advanced stage of 

 Johne's disease should be attempted, liecause, as regards the 

 immediate results, it is as a rule unlikely to prove profitable, 

 and still more because of the danger attaching to such animals 

 in the way of spreading the disease unless they are rigorously 

 isolated. 



Diagnosis of Johne's Disease. 



During the past year a material termed "■ Jolinin " has been 

 prepared on a considerable scale at the College and supplied 

 on demand, free of charge, for testing animals suspected of 

 Johne's disease. Johnin is prepared from artificial cultures 

 of the bacilli which are the cause of the disease, and it is 

 employed in exactly the same manner as tuberculin. It was 

 hoped that it might prove to be a specific test for Johne's 

 disease, but, unfortunately, it has been found that animals free 

 from this disease but affected with tuberculosis may also react 

 to it. This fact places a great difficulty in the way of employ- 

 ing Johnin for the detection of Johne's disease in a herd that 

 is not free from tuberculosis, and a further difficulty is created 

 by the long period which may elapse after infection before an 

 animal will react. Nevertheless, during the past two years in 

 a number of herds in which the disease had caused serious 

 losses great improvement has been effected by repeated testing 

 and elimination or isolation of the animals discovered to be 

 infected. 



Meml)ers of the Society who have reason to suspect the 

 existence of the disease among their animals may obtain advice 

 and assistance in dealing with it on application to the College. 



John McFadyean. 



Royal Veterinary College, 

 London, N.W. 



