INFECTIOUS DISEASES 227 



occurs enzootically and as an epizootic, sporadic cases 

 being rare. 



Etiology. This condition is caused by infection, but 

 the specific exciting cause has not been positively identi- 

 fied. The Staphylococcus pyogenes aureus has been 

 isolated from the lesions and was apparently present in 

 practically a pure culture. A Streptococcus appears to 

 be the exciting cause in some cases, and in other cases the 

 colon bacillus or some of its derivatives have been identi- 

 fied. Bacillus pyocyaneus sometimes causes this con- 

 dition. The young animals are predisposed to the 

 various types of infection by filthy surroundings and 

 improper care. Some breeders claim that if the sows 

 are permitted to farrow in clean quarters, and are main- 

 tained and fed in the proper way, that the pigs will not 

 contract this disease. 



There is evidence of the transmission of the disease 

 in utero from the dam to the foal in horses, but such 

 evidence has not been obtained in swine. 



The infection gains entrance through the thrombi in 

 the umbilical vessels. The infecting organisms extend 

 in the thrombus, ultimately reaching the blood stream, 

 by means of which they are disseminated throughout 

 the body. 



Lesions. The manifestations of this* disease are 

 variable and depend upon the number and virulency of 

 the infecting organism and their location in the body. 

 The typical lesions consist of omphalitis and suppurative 

 arthritis. Inflammation of the umbilical vessels may be 

 limited or there may be an accumulation of pus, the 

 inflammation being a typical suppuration and abscess 

 formation. The lesions of the joints are variable. 

 There may be a mild synovitis with limited or extensive 

 infiltration and tumefaction of the structures surrounding 

 the synovial membrane, in which cases the synovial mem- 

 brane is injected and tumefied. There is an increased 

 amount of fluid and it will be turbid and perhaps contain 

 flakes of coagulated material. In other instances the 

 synovial membrane will be distended with accumulated 



