DR. LEGEAR'S STOCK BOOK. 327 



affected, as the disease can in this way be carried from one animal 

 to another. The lymph or vaccine matter used to vaccinate 

 people for purposes of protection against smallpox is obtained 

 from cattle suffering from this disease. One attack gives proof 

 against subsequent attacks. 



ACTINOMYCOSIS LUMP-JAW. 



Lump-jaw is the formation of a peculiar tumor on the head, 

 more often the lower jaw. In some cases the soft tissues only 

 are affected, while in others the bone is diseased, the latter being 

 far more serious. In these latter cases the bone swells out and 

 becomes porous and honeycomb-like, and later on the jaw teeth 

 will become loose and fall out from the results of the bone 

 spreading away from the teeth. 



Causes. Lump-jaw is caused by a germ or fungus (actino- 

 myces or ray-fungus) which gets into the body from the food 

 or by an abrasion of the skin. It generally gains access through 

 a hollow tooth, and the germs, once in the jaw-bone, begin to 

 grow and multiply and disease the bone to such an extent that it 

 begins to swell and enlarge, causing the regular lump- jaw tumor. 

 These germs have frequently been found on the straw of certain 

 kinds of grain and grasses. 



Symptoms. The first symptom noticed in an enlargement on 

 the jaw. It may appear suddenly and grow rapidly, or it may 

 come on gradually and grow very slow. After a time they gen- 

 erally break and discharge a thick matter, and soon form into a 

 raw, unhealthy-looking sore. The matter that comes from the 

 tumor contains great quantities of the germs, and if discharged 

 on the pastures or in the feed troughs is dangerous to the other 

 cattle. The disease is far more prevalent in certain districts and 

 localities, as the germs are more prevalent in these places. An 



