DISEASES OF. CATTLE 305 



The symptoms of blackleg may be either of a general or a local 

 nature, though more frequently of the latter. The general symp- 

 toms are very much like those belonging to other acute infectious 

 or bacterial diseases. They begin from one to three days after the 

 infection has taken place with loss of appetite and of rumination, 

 with dullness and debility, and a high fever. The temperature may 

 rise to 107 F. To these may be added lameness or stiffness of one 

 or more limbs, due to the tumor or swelling quite invariably ac- 

 companying the disease. After a period of disease lasting from one 

 to three days the affected animal almost always succumbs. Death 

 is preceded by increasing weakness, difficult breathing, and occasion- 

 al attacks of violent convulsions. 



The most important characteristic of this disease is the appear- 

 ance of a tumor or swelling under the skin of the affected animal a 

 few hours after the setting in of the constitutional symptoms de- 

 scribed above. In some cases it may appear first. This tumor may 

 be located on the thighs (hence blackleg, blackquarter) , the neck, 

 the shoulder, the breast, the flanks, or the rump; never below the 

 carpal (or knee) and the hock joint. It more rarely appears in the 

 throat and at the base of the tongue. The tumor, at first small and 

 painful, spreads very rapidly both in depth and extent. When it is 

 stroked or handled a peculiar crackling sound is heard under the 

 skin. This is due to a collection of gas formed by the bacilli as they 

 multiply. At this stage the skin becomes dry, parchment-like, and 

 pool to the touch in the center of the tumor. If the swelling is cut 

 into, a frothy, dark-red, rather diagreeably smelling fluid is dis- 

 charged. The animal manifests little or no pain during the opera- 

 tion. 



As it is frequently desirable to know whether the disease is an- 

 thrax or blackleg, a few of the most obvious postmortem changes 

 may here be cited. The characteristic tumor with its crackling 

 sound when stroked has already been described. If after the death 

 of the animal it be more thoroughly examined, it will be noted that 

 the tissue under the skin is infiltrated with blood and yellowish, 

 jelly-like material and gas bubbles. The muscular tissue beneath 

 the swelling may be brownish or black, shading into dark red. It is 

 soft and easily torn and broken up. The muscle tissue is distended 

 with numerous smaller or larger gas-filled cavities, often to such an 

 extent -as to produce a resemblance to lung tissue. Upon incision it 

 does not collapse perceptibly, as the gas cavities are not connected 

 with each other. 



In the abdomen and the thorax blood-stained fluid is not infre- 

 quently found, together with blood-staining of the lining membrane 

 of these cavities. Blood spots (or ecchymoses) are also found on 

 the heart and lungs. The liver is congested, but the spleen is always 

 normal. 



Differential Diagnosis. Among the features of this disease 

 which distinguish it from anthrax may be mentioned the unchanged 

 spleen and the ready clotting of the blood. It will be remembered 

 that in anthrax the spleen (milt) is very much enlarged, the blood 



