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DISEASES OF THE DOMESTIC ANIMALS 



of the poison the application of moist clay, or antiphlogistine, or 

 cold water dressing, is desirable. 



Black Leg — Black Quarter— Quarter Evil of Cattle. 



Black leg attacks calves from the age of three months to two 

 years. Animals become inoculated through the skin by means of 

 the specific bacteria (B. chauvoei) in abrasions produced by thorns, 

 briars, barb wire, spines, etc. For this reason thin-skinned, grade or 

 pure-bred animals are those chiefly affected. The disease attacks 

 animals at different times according to the locality, and the season at 

 which the disease may be expected is well known by the cattlemen 

 in any region. Lack of exercise predisposes, so that in the spring 

 and fall, when feed is good, the disorder is apt to be more prevalent. 



Symptoms. — The characteristic swellings may appear in any 

 part of the body except on the tail or below the knee or hock. The 

 regions of the thigh and shoulder are commonly attacked ; also the 

 neck, chest, flank and rump. The swellings rapidly increase in 

 number and may coalesce. They give a crackling sensation on 

 pressure and are cool and without tenderness in the center. If 

 opened in the center there is no pain and a frothy discharge of 

 bloody serum exudes. The temperature is high (107" F. ), respira- 

 tion rapid (140), rumination ceases, and the animal lies down and 

 suffers from trembling or convulsions and has cold extremities. 

 Black leg commonly ends fatally within twelve to thirty-six hours. 



Autopsy shows that the subcutaneous tissue of the tumors is 

 distended with gas and that there is a black area of gangrene in the 

 centre of the swelling ; hence the name black leg, owing to the color 

 seen on removing the skin. The muscle in the tumor area has the 

 appearance of lung, so filled is it with small gas infiltrations, and 

 exudes a serous, bloody fluid when cut. Black leg may be distin- 

 guished from anthrax in that the spleen is not enlarged nor is the 

 blood thick and tarry as in anthrax. 



Malignant edema may closely simulate it but is associated with 



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