INFECTIOUS DISEASES OF CATTLE 319 



sections of the country where cattle-raising is engaged in exten- 

 sively. Outbreaks of the disease are most prevalent in the early 

 spring after the snow has melted, and in the late summer in 

 localities where cattle graze over the dried-np ponds and swampy 

 places in the pasture. The germs of black leg may be carried 

 from a farm where the disease is prevalent to non-infected prem- 

 ises by surface water. The opening up of drainage ditches 

 through stock-raising communities may be followed by out- 

 breaks of the disease. 



The symptoms of black leg develop quickly and may terminate 

 fatally in a few hours. These are gen- 

 eral dulness, stiffness, prostration and 

 loss of appetite. Lameness is a promi- 

 nent symptom. The animal may show a 

 swelling in the regions of the shoulder' 

 and hindquarters or on other parts of 

 the body. The swelling is very hot 

 and painful at first, but if the animal 

 lives for a time, it becomes less ten- 

 der, crackles when pressed on and the Fig. 119.— Baciiiusof emphysema- 



' tou3 anthrax. 



skin may feel cold and leathery. 



Fever is a constant symptom. In the highly acute form of the 



disease nervous symptoms, such as convulsions and coma, occur. 



The tissue changes in the region of the swelling are charac- 

 teristic. An incision into the swelling shows a bloody, dark 

 exudate and the surface of the muscular tissue is dark. Frothy, 

 bloody liquid escapes from the mouth, nose and anus. 



The preventive treatment consists in thoroughly draining 

 pastures and yards where cattle run. This measure does not 

 insure cattle against the disease. Cattle that die of " black leg " 

 should be cremated. This should be done at the spot where the 

 animal dies. If the carcass is moved or opened, the ground 

 should be thoroughly wet wnth a four per cent water solution 

 of a cresol disinfectant and covered with lime. 



