388 Veterinary Medicine. 



Symptoms. The period of incubation is two days, after inocula- 

 tion, and though it may appear to extend to a week when the 

 disease is contracted accidentally, it is impossible in such cases to 

 state the exact date of infection. The preliminary fever is not 

 always present, or recognized, yet there may be slight encrease 

 of temperature, partial impairment of appetite and rumination, 

 extra firmness of the faeces, a higher color of the urine, and above 

 all a slight diminution of milk, which is a little more watery and 

 coagulates more readily, than the normal. 



This is followed by heat and tenderness of the udder and the 

 appearance on the teats of small, pale-red nodules the size of a 

 pea or larger. In one or two days more the nodule, largely 

 encreased in size presents in the centre a depressed or umbilicated 

 bluish white portion, with a firm yellowish, reddish or reddish 

 blue margin, and outside this a soft pink areola, shading off into 

 the whitfe skin. The epidermis is raised at points by a viscid, 

 yellowish lymph, enclosed in a series of saccules (multilocular 

 vesicle). The vesicle encreases to 8 or lo lines in diameter by 

 the eight or tenth day, and exceptionally, the umbilication is 

 effaced by the excessive production of lymph. If left unbroken 

 a brownish shade appears in the centre and gradually extends 

 toward the periphery, the contents becoming purulent, and the 

 pustule gradually drying up to form a crust. The drying and 

 thickening of the crust goes on until the fourteenth day and the 

 crust is usually detached by the twentieth, leaving a pale rose 

 colored, smooth, shallow depression, which forms the permanent 

 pit left after the skin has healed. The primary scabs usually 

 show the central umbilication, and always the conical projection 

 in the center of the deep aspect, and corresponding to the pit. 



Vesicles on the mammae may pass through the above stages, 

 but those on the teats are usually ruptured by the hands of the 

 milker as soon as the liquid is thown out, and this gives rise to 

 troublesome sores, with complex infections, at times implicating 

 the gland tissue so as to cause destructive mammitis with loss of 

 one or more^quarters, and in any case abraded and Irritated at 

 each milking, so that the animal resists handling, the milk is 

 drawn off imperfectly, and dries up or the cow becomes an invet- 

 erate kicker. If the milker has not been vaccinated he is liable 

 to contract the disease. 



