LECTURE XXIX. 

 ACTINOMYCOSIS OR LUMPY JAW. 



Definition.— This disease is commonly called either lumpy- 

 jaw or big-head. It is characterized by the development of pe- 

 culiar enlargements, usually around the head. The disease may 

 also affect internal organs. 



The tumors and abscesses which characterize this disease 

 probably have a common origin, being due to the presence and 

 activity of a vegetable organism known as actinomyces. When 

 these abscesses are opened there is usually found in the interior, 

 pus containing minute yellow sulphur-like grains ; sometimes very 

 abundant. These yellow grains may be bedded in the diseased 

 soft tissues of the tumors. Seen under a microscope this fungus 

 under certain conditions seems to be composed of radiating club- 

 shaped particles. As the fungus multiplies and spreads the tumor 

 growths increase. The tumors are usually very firm on account 

 of the large amount of connective tissue which they contain. 

 The interior of the tumor is usually somewhat honeycombed with 

 the fungus colonies in the spaces. Animals affected are chiefly 

 cattle, horses and sheep. 



Relation to public health. — Human beings are evidently 

 susceptible to inoculation from this disease, but as the affected 

 parts of diseased carcasses are not commonly used as articles of 

 human food, and animal meats as a rule are cooked before being 

 eaten, there is ordinarily comparatively slight danger for human 

 beings. The government meat inspection regulations pass car- 

 casses which are but slightly and locally diseased, and condemn 

 those which are extensively and generally diseased. 



Parts involved. — These are commonly the bones of the upper 

 and lower jaws ; the soft tissues between the two branches of the 

 lower jaw^ and the tongue. These are the external or superficial 

 portions of the body most commonly affected. This disease some- 

 times affects the lungs and other internal organs and might be 



