Commissioner of Agriculture 277 



incubation after experimental inoculation, or actual penetration 

 into the tissues, is usually two davs, and this is the most common 

 period of delay when the animals have been exposed in a public 

 market or infected car, and have taken the virus on the tongue or 

 between the toes. 



The first indication of derangement of health is a rise of the 

 body temperature to 103°— 105° F., as shown by the thermometer 

 introduced into the rectum. In some mild cases this rise of tem- 

 perature may be so slight as to elude observation. There may be 

 some attendant erection of the hair and coldness of the lower parts 

 of the limbs, of the ears, and of the horns when present. There 

 may follow drooping of the head and ears, slight trembling or even 

 distinct shivering, dryness and heat of the muzzle, redness, tender- 

 ness and extra warmth of the lining membrane of the mouth and 

 of the tongue, and very soon a driveling of saliva in ropy strings 

 from the mouth. The tenderness of the mouth increases, there is 

 grinding of the teeth, the accumulation of a white frothy mass on 

 the lips, and a tendency to move the jaws, making a smacking 

 sound with the lips, tongue and roof of the mouth, which may be 

 heard at some distance. At this time there is suspension of feed- 

 ing and chewing the cud, not so much from sickness as from the 

 pain caused by mastication. The body temperature tends to go 

 down as the discharge increases and the local eruption appears. 

 By the second day of illness an examination of the mouth will 

 usually detect round blisters formed by elevation of the cuticular 

 layer, and growing from one-tenth to one-half an inch in diameter. 

 These blisters appear by preference on the dental pad on the front 

 of the upper jaw where the incisor teeth appear in other animals, 

 on the tongue, or on the gums or inner sides of the lips. They 

 may appear as isolated blisters, each rising into a nearly evenly 

 rounded bubble which early bursts, leaving a circular, red, and 

 at first even angry raw surface. In other cases they run together, 

 to form patches or strips, and as they burst and shed the cuticular 

 layer, the resulting red, raw surface may extend in a continuous, 

 unbroken line across the whole length of the dental pad, or from 

 the tip of the tongue back for an inch or two on both upper and 

 lower surfaces. The blisters often appear along the whole length 

 of the tongue, especially on its upper surface, on the roof of the 



