120 MASTITIS OF THE COW 



be impossible and is of no practical significance, since 

 wound-infection is seldom treated as a single infection, but 

 as a mixed infection. 



The chrome wound-infections are pyobacillosis, tuber- 

 culosis and actinomycosis. 



These complicated infectious wounds show little or no 

 tendency to heal, but gradually become larger. 



Fever can occur in complications with acute infections 

 (mixed infection). In gangrene, fever is always present, 

 otherwise these infections are free from fever. 



All these chronic infections spread into the udder-tissue, 

 which often manifests a widely circumscribed hard swelling 

 around the wound, together with alteration of the milk 

 (see under Specific Udder-infections). 



In pyobacillosis the wound-secretion is thick and yellow, 

 the consistency of cream or salve, and contains no calcareous 

 granules. The walls of the wound are composed of smooth, 

 firm and tough connective tissue, which is colored green 

 in gangrene by pigment of putrefaction. Gangrene is very 

 common. The corresponding lymph-gland is not enlarged. 



In tuberculosis the secretion is yellow, soft, caseous and 

 f requentl}^ contains calcareous granules which are easily felt 

 by rubbing the pus between thumb and finger. The walls 

 of the wound are often irregular and nodular with tubercles. 

 Gangrene is very common. The corresponding lymph- 

 gland is enlarged. 



In actinomycosis the quantity of the secretion is usually 

 small, qualitatively it is yellow and viscid, due to disin- 

 tegration of actinomycomata. The wound may become 

 filled with red, soft, spongy granulation tissue which may 

 protrude from the wound as a great oval red nodular actino- 

 mycoma. The wound does not heal, but gradually in- 

 creases. Gangrene is not so common because of the small 

 quantity of the secretion. The corresponding lymph-gland 

 is usually not enlarged. 



