CHAPTER III 



SYMPTOMS AND DIAGNOSIS 



Clinical Symptoms. — In the early stages of Johne's 

 disease there are no symptoms from which a positive 

 diagnosis can be made. In inspecting a herd of cows 

 in a byre at milking time, one or two may be picked 

 out which are apparently unthrifty. Their coats are 

 erect or staring, and their general condition is poorer 

 than that of their neighbours, although they have 

 received the same care and attention. Usually the 

 history of these animals shows that the extra food 

 given to improve their condition has produced no good 

 effect. In course of time they have slight attacks of 

 diarrhoea, lose more flesh, and give less milk. In the 

 case of a pregnant cow^ the additional strain of supply- 

 ing the needs of the growing foetus hastens the 

 progress of the disease, the diarrhoea becomes more 

 frequent and severe, and emaciation more marked. 

 Parturition, and the consequent activity of the mam- 

 mary gland, often produces a fatal result within a few 

 months of calving. Sometimes the symptom of diar- 

 rhoea is not shown until after calving, and yet the 

 cow may die within a few months of its onset. The 

 course of the disease depends somewhat on the diet 

 and general hygiene. Although Miessner considers it 

 a disease of stall cattle (Stallseuche), as a rule the 

 symptoms are increased in severity when the cattle 



21 



