344 TwENTY-FiEST Biennial Eepobt 



Black Leg. 



This is an acute, infectious disease affecting cattle, 

 and very often other ruminants and swine. It is caused 

 by an anerobe known as the Bacillus Emphysematosa, 

 which may reproduce itself in the soil or pastures. This 

 germ when entering the system produces the disease, 

 which is characterized by local, crepitant swellings at al- 

 most any point on the body or limbs above the knees and 

 hocks. It is most commonly found affecting animals 

 between the ages of four months and two years, and is 

 occasionally found in suckling calves , and in animals 

 three or four years of age, when such animals are placed 

 on infected pastures. All breeds of cattle are equally 

 susceptible, but pure bred cattle are less frequently at- 

 tacked because of the better attention which they re- 

 ceive. The excretions from diseased animals may re- 

 main virulent for an indefinite period after coming in 

 contact with the earth and may transmit to a healthy 

 animal the disease through a skin abrasion while the ani- 

 mal is lying on the ground contaminated with the virulent 

 excretions of a diseased animal or the carcass of one 

 dying from the disease. Black leg is a disease that is 

 connected with infected soil, and the bacUli seem to 

 be capable of reproducing the disease and preserving its 

 virulency even under unfavorable conditions. The bac- 

 teria from diseased animals also remain virulent in the 

 soil. There is no doubt but that these facts wiU account 

 foy the disease re-appearing in the same locality or in 

 the same pastures when susceptible animals are placed 

 thereon year after year. Animals may also become in- 

 fected by eating infected feed or drinking water from 

 streams into which bacteria have been washed from in- 

 fected grounds. This is a disease that is not difficult to 

 diagnose, as the symptoms manifested are characteris- 

 tic. Among the first conditions noticed is lameness. In 

 a very short while it will probably be noticed that the 

 animal is down and unable to rise. Upon examination a 

 distinctly circumscribed swelling will be found usually 

 in the region of the shoulder or the hip, occasionally 

 below the hip or the stifle. This condition is often mis- 

 taken for a bruise, leading the owner to believe that the 



