470 DISEASES OF CATTLE. 



tifically known as miasmatic diseases ; that is, they remain stationary 

 in stables with damp floors, low ceilings, poor ventilation, and bad 

 sanitaiy conditions in general. Such places furnish a favorable seat 

 of propagation for the infective material, and it will remain actiAe 

 for a long time, causing the loss of a few animals each year. One 

 European veterinarian reports an instance in which the disease re- 

 mained for 25 years on the same farm, attacking in all 225 animals, 

 with a mortality of about 98 per cent. 



The disease is most common in late winter and early spring, at all 

 altitudes, and has a special preference for young, well-nourished 

 cattle, although older animals are not immune. The time between 

 the entrance of the infective principle into the body of the animal 

 and the appearance of the first symptoms is relatively very long, 

 averaging, according to German investigators, from 20 to 30 days. 

 Fortunately, it is not a disease which spreads to any great extent 

 or which causes severe losses, and hence legislative enactments do 

 not seem to be necessary for its restriction. 



SymptoTns. — These are extremely variable according to the point 

 of localization of the lesions. It is usually ushered in with a chill, 

 followed by a marked rise of temperature (104° to 107° F.). The 

 Lead droops, the skin is hot and dry, and the coat staring. Quiv- 

 ering of the muscles in various parts of the body is frequently 

 observed. Marked dullness of the animal, passing, according to 

 some observers, into an almost stupefied condition later on, is quite 

 common. The secretion of milk stops in the beginning of the dis- 

 ease, and loss of flesh, invariably associated with the disease, is 

 extremely marked and rapid. The lesions of the eyes may best be 

 likened to moon blindness (periodic ophthalmia) in horses. 



There is first an abundant secretion of tears, which run down the 

 face. The lids are swollen and inflamed, and indeed this may be so 

 marked as to cause involuntary eversion, exposing the reddened 

 conjunctiva to view. Sunlight is painful, as is shown by the fact 

 that the animal keeps the eyes continuouslj^ closed. This inflamma- 

 tion may extend to the cornea, causing it to assume a slightly 

 clouded appearance in mild cases or a chalky whiteness in more 

 severe affection . Cases of ulceration of the cornea followed by 

 perforation and subsequent escape of the aqueous humor, leading to 

 shrinking of the eyeball and permanent loss of sight, have been re- 

 corded, but these are relatively rare, although slight inflammation of 

 the deeper structures of the eye (iris) are more frequent. In mild 

 cases this inflammation may undergo complete resolution, but more 

 frequentlj^ permanent cloudliness of the cornea, either diffuse or in 

 spots (leucoma), is the result. The mucous membrane of the mouth, 

 nose, sinuses of t4ie head, throaty and lower respiratory passages are 



