122 PEINOIPLES OF 7ETEKINAET SUBGEKY 



is seen, from ■wMch. one or more nut to egg sized tumors pro- 

 ject. These tumors eventually break tkrough the overlying 

 skin and appear reddish, fungoid-like masses. Then, again, 

 the original swelling becomes an abscess, bursts, discharging 

 a creamy pus, the abscess cavity later filling with a fungus- 

 like growth, eventually projecting beyond the opening 

 through which the pus was emptied. The tumors seen in the 

 pharynx are either pedunculated or have a broad basis, inter- 

 fering with respiration and deglutition. When invading the 

 bone, the latter enlarges decidedly. The actinomycotic 

 growth may grow outward, break through muscle and skin, 

 and appear as a mushroom-like mass, or the growth may take 

 an inward course and appear in the mouth. 



What forms of actinomycosis are observed ? 



External, internal and generalized — the latter very rare. 

 What animals are liable to actinomycosis ? 



Primarily, cattle ; at times, horses, swine and sheep. 

 How are animals infected ? 



Usually through the ingestion of actinomyces-bearing 

 food coming in contact with wounds of the mucous mem- 

 brane of the mouth. 

 Describe actinomycosis of the bones. 



Maxillary bones of cattle : The disease takes its start in 

 the gums near a tooth, leading to an ossifying periostitis with 

 formation of an exostosis. In those cases where the actino- 

 mycoma spreads to the marrow, a rarefying osteitis results. 

 In both the ossifying periostitis and rarefying osteitis, the 

 superior and inferior maxillary bones become greatly en- 

 larged. After having invaded the bone, the actinomycotic 

 granulation tissue may appear in the mouth, loosening teeth, 

 or may even extend into the maxillary or frontal sinuses. 



