CHAPTER IV 



PROGNOSIS, TREATMENT, AND PROPHYLAXIS 



Prognosis. — It has been stated that in some cases of 

 Johne's disease recovery takes place. Le Sueur has 

 informed us that in Jersey he has noted that adult cows 

 put on to affected land do not contract the disease. If 

 these animals have not been previously in contact with 

 affected cattle or exposed to risk of infection, it must 

 be supposed that the natural resistance to the disease 

 is increased with age ; but it may be that the animals, 

 having already contracted the disease in a mild form, 

 and having subsequently recovered before the develop- 

 ment of clinical symptoms, have acquired thereby an 

 active immunity. 



M'Fadyean mentions a case that he believed to be 

 one of recovery. He says : ** The exceptional case was 

 a yearling which, along with a cow on the same farm, 

 developed symptoms of the disease. . . . Soon after- 

 wards the cow was killed and the disease verified at 

 the post-mortem examination. The yearhng, although 

 not medicinally treated, gradually ceased to scour, and 

 gained a little in condition. It was killed six months 

 after admission, and the post-mortem examination 

 showed that the intestine was normal in appearance, 

 while none of the characteristic bacilli could be de- 

 tected with the microscope." In the case thus de- 

 scribed the animal had certainly been exposed to great 



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