94 THE COW IN HEALTH AND DISEASE 



and broken down. This process gradually 

 spreads but it sometimes requires several 

 months to bring about the death of the animal. 

 These lesions may also be found inside the 

 bones, within the spinal cord or the brain and 

 this is the reason that some animals are killed 

 after reacting to the tuberculin test and no 

 signs of the disease can be found. 



Symptoms of Tuberculosis. 



It may seem very strange to hear it said 

 that there are no symptoms by which tuber- 

 culosis can be recognized with any certainty in 

 the live cow but such is the case. There are 

 cases of tuberculosis in which a diagnosis can 

 be made, but these cases are usually very pro- 

 nounced cases and are also very rare. There 

 are very many symptoms that would make one 

 suspicious of tuberculosis, but many times 

 these are not noticeable; we have observed 

 many surprised cow owners when having their 

 herds tested, at the large number of reactors 

 that were found. Since about 10 per cent of 

 the cows in the United States are thought to 

 be tubercular, it is well to suspect this disease 

 in all untested cows that show any signs of a 

 constitutional disturbance that tends to be 

 chronic. 



Cows that lose flesh and remain thin even 

 with good care and feed ; that have a dry harsh 

 coat of hair that is staring; that have an irre- 

 gular appetite, or digestive troubles ; those that 



Digitized by Microsoft® 



