414 The Diseases of Animals 
day and gradually increasing the time as the animals 
become accustomed to the change of food. It is prob- 
able that several diseases are often confused under 
the name “cornstalk disease.” 
“BIG JAW,” OR ACTINOMYCOSIS OF CATTLE 
This disease is also called “lump jaw,” and in some 
localities the bunches, or tumors, are called wens. 
Actinomycosis is due to a vegetable organism that gains 
entrance to the tissues, and, growing, produces a lump 
or tumor, which may grow toa large size. It usually 
occurs in the region of the head or neck. Figs. 57, 58. 
The first symptom is a slight swelling, such as might 
come from an injury, usually appearing on the face or 
lower jaw. In most cases the enlargement is due to the 
bulging outward of the bone, the fungus causing the 
disease having gotten inside the bone by working its 
way along the roots of the teeth. As the disease pro- 
gresses, the tumor becomes larger and finally breaks, dis- 
charging a thick, sticky pus, but it does not diminish 
much in size as a result of this discharge. It may heal 
temporarily, but it gradually increases in size and, later, 
breaks again. The teeth in the affected part often be- 
come ulcerated and the jaw sore, so that the animal is 
unable to chew its food properly. Actinomycosis is 
rarely seen in calves. 
If a drop of the pus from an actinomycotie tumor is 
spread out thinly on a piece of glass, minute yellow 
specks can be seen with the naked eye. If these specks 
are placed under a microscope and slightly flattened, 
