IMPORTANT INFECTIOUS DISEASES 469 
withers are caused from external injury—the animal 
rolling on a rock, ill-fitting collars, or the saddle press- 
ing on the withers. Tooth fistulae are caused by a de- 
cayed tooth; sternal fistule by injury in the breast; 
salivary fistule by an injury to the tube which carries 
the saliva from the gland to the mouth. 
At first a swelling appears, which enlarges and becomes soft. 
The fluid contained in it can be distinctly felt. If left to itself the 
swelling gets larger and softer, and in a month or so breaks and 
discharges the contents. The fluid that comes from the swelling is 
first thin and streaked with blood; later_it con- : 
tains yellow-appearing masses or pus. The in- 
closing sac is a hard, firm membrane that keeps 
the wound from healing. The wound may heal 
and there will be no pus discharged for a month, 
then the old opening will be broken and the pus 
will flow out again until the sacis emptied. This 
healing of the wound and then breaking again 
may be kept up for years unless the disease is 
properly treated by a trained veterinarian. 
5. Foot and mouth disease—This 
malady usually affects ruminants, and 
spreads very rapidly. The virus which 
transmits the disease may be carried by 
railroad cars, bedding, feeds, dairy 
products, small animals and _ persons. 
In from three to five days after infec- 
tion the animal has a moderate fever. yoo; anp MouTH 
The appetite is lost and the mouth is kes 
closed. There is a dribbling of saliva, tiene’ eta 
and in two or three days yellowish white "°° 
spots, the size of hemp. seeds, appear on the gums, the 
lower surface of the tongue, lining of the mouth, and on 
the lips. These eventually attain the size of a silver 
dollar. They run together, burst and form painful, foul- 
smelling ulcers. 
Usually, a short time after an appearance of the disease in the 
mouth parts, there is a redness, heat and swelling of the skin at its 
juncture with the hoof, and especially between the toes and upon the 
