22 JOHNKS DISEASE 



are turned out to pasture. In some cases it is possible 

 to prolong the life of an affected animal for many 

 months by placing it in a warm house and supplying 

 an easily digestible nitrogenous diet. The diet seems 

 to play an important part in the progress of the con- 

 dition. We have produced the disease in several 

 calves in inoculation experiments : six months after 

 inoculation the animals v^ere killed, and found to have 

 lesions of the disease, and to shov;^ acid-fast bacilli in 

 these lesions. When killed, the calves v^ere in poor 

 condition, thin and hide-bound. For some days one 

 was unable to rise without assistance; but on post- 

 mortem examination this animal showed tuberculosis 

 of the mediastinal glands as well as Johne's disease. 

 None of these calves, however, had shown signs of 

 diarrhoea. From the time of inoculation onwards the 

 faeces, examined frequently for the presence of acid- 

 fast bacilli, gave negative results, although for about a 

 fortnight the faeces of one calf contained a large number 

 of semi-acid-fast bacilli. These calves were fed for a 

 time on milk (previously boiled to avoid tubercular 

 infection) with the addition of a little cod-liver oil; 

 later they were given good meadow hay and occasion- 

 ally a little lucerne or other green food. 



Bang noticed diarrhoea in calves at the eighth month 

 after feeding with large quantities of infected intestine, 

 and probably, at grass, our own animals would have 

 shown symptoms of diarrhoea ; but in naturally infected 

 animals, the period from the time the bacilli begin to 

 multiply in the intestinal mucosa to the onset of 

 diarrhoea is rarely less than six months, and in well- 

 fed animals it may be much longer. Probably it will 

 be shortened in the case of animals in exposed situa- 

 tions on poor pasture, in pregnant cows, and in those 

 which are suffering from tuberculosis, strongylosis, or 



