MORBID ANATOMY 209 



Actinomycosis is not a rapidly fatal disease. Animals 

 rarely if ever die from its immediate effects. The length of 

 time during which they survive depends very largely upon the 

 location of the tumor and the rapidity of its development. If 

 the tumor is situated where it does not interfere seriously with 

 prehension, mastication or swallowing of food or w^here it 

 does not occlude or press upon the respiratory passages the 

 animal usually survives for several years. When death occurs 

 it is usually due to inanition, the animal being unable to take 

 sufficient food, although the drain upon the system by the 

 long continued discharge of pus must be severe. Mayo 

 reports several cases where the disease was watched for five or 

 six years and where it would probably have continued several 

 years more had the animals not been destroyed. Most animals 

 which become affected with actinomycosis are either destroyed, 

 treated or slaughtered for beef in the early stages of the 

 disease. 



§ 166. Morbid anatomy. The actinomycotic tumors 

 have in or near their centers rosettes of the ray fungus 

 surrounded by cells. The newly formed tissue consists princi- 

 pally of epithelioid and spindle shaped, connective tissue cells, 

 among which giant cells may appear. As these cells increase 

 in number they press against the surrounding tissues produc- 

 ing the hard and dense tumors. This is especially true when 

 they are located in the connective tissue. In certain other 

 positions, such as the liver, the inflammatory cells are sur- 

 rounded by a fibrous tissue framework which gives to the 

 lesion a honey comb appearance. On section a disagreeable 

 "nutty" odor is given off which Mayo considers to be quite 

 characteristic of the disease. The outside of the tumor is 

 usualh^ composed of a dense layer of fibrous connective tissue. 

 Extending from the periphery toward the center, the tissue 

 becomes less dense and is composed largely of epithelioid cells. 

 In the softer tissue there are often cavities of greater or less 

 size filled with a viscid, purulent substance in which the small, 

 yellowish granules of the ray fungus can be found. If this 

 pus is spread in a thin layer on a smooth surface granules 

 composed of this fungus growth can often be seen with the 



