INFECTIOUS DISEASES OF CATTLE. 45T 



investigators points to malignant catarrh as being of specific origin ; 

 that is, due to some form of microorganism the contagious character 

 of which is poorly developed. This accounts for the slow transmissi- 

 bility 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 sani- 

 tary conditions in general. Such places furnish a favorable seat of 

 propagation for the infective material, and it will remain active for a 

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

 One European veterinarian reports an instance where this disease 

 remained for twenty-five 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 cpring, 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 twenty to 

 thirty 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. 



Symptoms. — 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 con- 

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

 the animal keeps the eyes continuously closed. This inflammation 

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

 appearance in mild cases or a chalky whiteness in more severe affec- 

 tions. 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 recorded ; but these 

 are relatively rare, although slight inflammation of the deeper struc- 

 tures of the eye (iris) are more frequent. This inflammation may 

 undergo complete resolution in mild cases, but more frequently per- 



