INFECTIOUS DISEASES OF CATTLE 317 



The specific cause of actinomycosis is commonly known as 

 the ray fnngns (Fig. 118). This fungus grows on certain plants, 

 and the animal usually contracts the disease by eating plants 

 or roughage that have the fungus on them. Grasses having 

 awns that are capable of woundirig the mucous membrane of 

 the mouth and penetrating the gums are most apt to produce 

 the disease. Young cattle that are replacing and erupting their 

 teeth are most prone to " lumpy jaw." (Conditions that favor 

 bruising of the jaw and external wounds favor the develoj^ment 

 of actinomycosis. 



The fungus grows in the tissues, causing an inflammatory 

 reaction and destruction of 

 the tissue. The ray fungus 

 can be seen in the diseased 

 tissue or the pus as yellow- 

 ish, sj)herical bodies about the 

 size of a grain of sand. Each 

 of these bodies is formed by 

 a large number of club-like 

 bodies arranged about a cen- 

 tral mass of filaments, il W "ft^'' 



The local symptoms are ir 1,0 -ru t 



•J L Fig. 118, — The ray fungus. 



characteristic (Fig. 117). 



The tumor may involve the soft tissues of the head. If the jaw- 

 bone is affected the tumor feels hard and cannot be moved about. 

 Sometimes it is soft and filled with pus. Tumors of long stand- 

 ing may possess uneven, nodular surfaces and fistulous openings. 

 When the tongue is affected, it is swollen and painful, and 

 prehension and mastication of the food may be impossible. 

 A\Tien the pharynx is the seat of disease, breathing and swallow- 

 ing are difficult and painful. Actinomycosis of the lungs may 

 present the appearance of a chronic pulmonary affection. If the 

 disease involves the head and lungs, the animal may become 

 unthrifty and emaciated. In doubtful cases a microscopic ex- 



