INFECTIOUS DISEASES 295 



The specific cause of this disease is tlio Bacillus septicemia 

 hemorrhagica (Fig. 101). 'riiis hacillus probably enters the 

 body tissues by way of the lining membrane of the intestinal and 

 respiratory tracts. In the northern States, cattle pasturing on 

 marsh and swr.mpy pastures are more often affected with the dis- 

 ease in the late summer and fall than at other seasons of the year. 



The drinking of contaminated surface water that collects 

 in muddy pools and ponds may cause the disease. Cattle pas- 

 turing in stalk fields sometimes become 

 infected in this way. Dusty sleeping 

 quarters and small, crowded, muddy 

 yards seem to favor the development 

 of the disease in hogs. Exposure, 

 insufficient exercise and careless feed- 

 ing are the predisposing factors. 



The st/mploms vary according to 

 the animal and organ, or organs of 

 the body an^ected and the violence oi hemorrhauica. 



the attack. The disease may be acute or subacute. The brain 

 and its membranes, lungs and air-passages and intestines may 

 become affected. The symptoms may be classed under the head 

 of nervous, respiratory and intestinal (Fig. 102), and they may 

 be very unsatisfactory from the standpoint of diagnosis. The 

 history and post-mortem lesions are of most value in the recog- 

 nition of this disease. The local conditions, the loss of several 

 animals in the herd and the finding of hemorrhagic lesions in the 

 different body tissues may enable the examiner to correctly diag- 

 nose the disease. It is very advisable in order to confirm the 

 diagnosis to make a bacteriological examination of the tissues. 



The acute form of the disease is very fatal. Animals that 

 have the subacute form usually recover. The death-rate is be- 

 tween five and fifteen per cent of the herd. The mortality is 

 heavier than this unless prompt preventive measures are taken. 



Preventive treatment is of the greatest importance. Cattle 

 that become affected when running on pasture should be moved, 



