INFECTIOUS DISEASES 231 



food, infected premises, hides and in the various animal 

 serums. 



In the 1914 outbreak in the United States several 

 centers of infection were undoubtedly established through 

 the use of anti-hog cholera serum that had been made 

 from infected hogs. This latter source is of considerable 

 importance and should entail careful inspection upon^the 

 part of the government employes to prevent a distri- 

 bution of the disease by this means. 



The usual channel of entrance of infection is through 

 the abrasion of the buccal mucous membrane, but in 

 hogs the infection is more frequently affected through 

 abrasion of the skin in an interdigital space or around the 

 superior part of the hoof. Such abrasions are no doubt 

 of very common occurrence as they can easily be produced 

 by stubs, sticks and splinters which are very common' in 

 the pens where hogs are maintained. Infection can also 

 be introduced upon food stuff, especially by milk from 

 affected cows and thus gain entrance to the lesions to 

 abrasions in the mouth, and as before stated infection 

 may be introduced in serum. Some authorities are of 

 the opinion that the disease may be carried from farm 

 to farm by birds and other carrion animals and thus an 

 absolute quarantine should be maintained on all infected 

 premises. 



Lesions. Foot-and-mouth disease assumes two 

 forms, benign and malignant. As a rule hogs are not 

 as seriously affected with this disease as are cattle, a 

 subacute or benign form being most prevalent in these 

 animals. The principal manifestation of this disease 

 consists of vesicles which develop around the coronary 

 band and in the interdigital spaces. One or more feet 

 may be involved and these vesicles vary in size from a 

 grain of wheat to a pea, and are usually of short duration. 

 The surface of the epithelium ruptures and later des- 

 quamates, leaving a denuded surface. The surrounded 

 surface becomes tumefied and hypersensitive. Similar 

 lesions may also be found on the skin of the snout and 

 less frequently upon the buccal mucous membrane. If 



