INFECTIOUS DISEASES OP CATTLE. 475 



tively rare in this country, being more common on the continent of 

 Europe, Outbreaks have occurred, however, in Minnesota, Xew 

 York, and New Jersey. The casual agent of the disease has as yet 

 never been isolated, and inoculation experiments with the view of 

 artificially reproducing the disease have proven negative in every 

 case. In spite of the foregoing statements the consensus of opinion 

 of eminent investigators points to malignant catarrh as being of 

 specific origin; that is, due to some form of microorganism the con- 

 tagious character of which is poorly developed. This accounts for 

 the slow transmissibility of the disease from one animal to another. 

 In fact, malignant catarrh is a type of that class of affections which 

 are scientifically known as miasmatic diseases; that is, they remain 

 stationary in stables with damp floors, low ceilings, poor ventilation, 

 and bad sanitary conditions in general. Such places furnish a favor- 

 able scat of propagation for the infective material, and it will re- 

 main active for a long period of time, causing the loss of a few 

 animals each year. One European veterinarian reports an instance 

 where the disease remained for 25 years on the same farm, attack- 

 ing in all 225 animals, with a mortality of about 98 per cent. 



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

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

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

 between the entrance of the infective principle into the body of the 

 animal and the appearance of the first symptoms is relatively very 

 long and, according to German investigators, averages from 20 to 

 30 days. Fortunately, it is not a disease which spreads to any gi-eat 

 extent, or which causes severe losses, and hence legislative enact- 

 ments do not seem to be necessary for its restriction. 



Sj/mptoms. — These are extremely variable according to the point of 

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

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

 droops, the skin is hot and dry, and the coat staring. Quivering 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 disease, 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 over 

 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 continuously closed. This inflamma- 

 tion may extend to the cornea, causing it to assume a slight clouded 



