450 CHRONIC INFECTIOUS DISEASES 



toms are progressive emaciation and anemia. An inter- 

 mittent diarrhea is an almost constant symptom. The feces 

 are thin, gruel-like, or watery, and discharged without 

 . straining. In a few cases there may be no diarrhea although 

 the emaciation and anemia are present. 



The general condition of the patient gradually becomes 

 bad. The animal grows very weak, the appetite capricious, 

 lactation ceases, the hair coat is dull and erect, the eyes 

 sunken, the body thin and wasted. 



Diagnosis. — As the symptoms are not especially character- 

 istic, in the absence of a necropsy the diagnosis is difficult. 

 The microscopic examination of the feces and scrapings 

 from the wall of the rectum for the specific bacillus is helpful, 

 but not very reliable, as often the rectum is not involved 

 and from the feces usually only a few bacilli can be obtained 

 which must be differentiated from tubercle bacilli and non- 

 pathogenic acid-fast bacteria. 



0. Bang recommends testing the suspected cattle with 

 tuberculin prepared from avian tubercle bacilli. Cattle 

 affected with Johne's disease react to this form of tuberculin 

 somewhat as do tubercular cattle to bovine tuberculin. The 

 post-injection temperatures may reach as high as 105.8° F. 

 As a rule, however, the post-injection temperatures are lower 

 than in tuberculosis. Often associated with the rise in tem- 

 perature occur constitutional disturbances, such as chill, 

 diarrhea, etc. While tubercular cattle react to avian tuber- 

 culin, those affected with Johne's disease do not react to 

 bovine tuberculin. It is recommendable, therefore, to employ 

 both tuberculins in suspected cases, that tuberculosis be 

 excluded. By thus testing and destroying the reactors the 

 disease has been eradicated from a few herds in England. 



Course. — The course is prolonged, extending over several 

 months. It seems to be favorably influenced by an open-air 

 life, but close confinement, advanced pregnancy, and par- 

 turition affect the course adversely. 



Prognosis. — The prognosis is bad. Cases which may be 

 recognized clinically, die in a few weeks to a few months. 



Treatment. — No successful treatment has yet been devised. 

 The destruction of the diseased animals prevents further 

 spread. 



Digitized by Microsoft® 



