BACILLUS NECROPHORUS INFECTIONS 175 



Calves have a similar trouble (calf diphtheria) due to the 

 same virus and characterized by patches of diphtheritic mem- 

 brane in the mouth, nose, larynx, and even the trachea. The 

 necrotic areas in calves are much larger than in pigs. 



Symptoms. — Canker sore mouth is easily recognized by the 

 small ulcers which are most common in the mouth or on the 



Fig. 59. — Lip-and-Leg Ulceration. (B. A. I.) 

 Produced by artificial infection with Bacillus necroplwrus. 



skin near the mouth. They may invade the nose and adjacent 

 cavities, and the trachea, and even extend to the intestines. 



Prevention and management. — Keep brood sows and pigs 

 away from the foot-rot of cattle and sheep and from what may 

 be necrotic enteritis in other hogs. Avoid old pens and yards. 

 In case of outbreak, only the most thorough cleaning and re- 

 peated disinfection will suffice. 



"When the season permits, it may be necessary to move sows 

 and litters repeatedly to fresh grounds, and in some cases, it 

 may pay to clean and disinfect the sow's belly before the pigs 

 are allowed to nurse. 



