Lung Plague in Cattle. 611 



Symptoms . These vary greatly with the animal and its environ- 

 ment. Other things being equal it may develop more suddenly 

 and violently in the cbese Shorthorn, Angus, Hereford, Ayrshire 

 or Dutch, and less so in the spare Brittany or Jersey. In very 

 hot weather the attack is very sudden and severe. A chill from 

 exposure, an attack of bronchitis or pneumonia, the excitement 

 attendant on parturition, on travelling by rail or driving may pre- 

 cipitate and aggravate the seizure. Under some such conditions 

 there may be sudden and extreme hyperthermia, rapid pulse, op- 

 pressed breathing, percussion and auscultation evidence of ex- 

 tensive pulmonary consolidation and death in two or three days, 

 while the body is still plump and fat. 



Individual susceptibility appears to have influence, the same 

 stable presenting simultaneously cases of acute and fatal type and 

 others that are slow, and insidiously progressive. In newly in- 

 vaded countries and in bovine families that have not been ex- 

 posed to the infection for many generations the tendency is to a 

 higher proportion of severe and fatal cases, while in herds native 

 to districts that have been continuously or frequently exposed, 

 mild cases tend to predominate. The more susceptible strains of 

 blood have been killed out, and the surviving strains show a 

 greater power of resistance. 



Apart from the predisposing environment the tendency of lung 

 plague is to set in slowly, insidiously, and for a time almost with- 

 out outward symptom. For a week, fortnight, month or more 

 there may be a slight cough heard only at rare intervals and 

 neither painful nor specially troublesome. Though sometimes 

 hard, it is more commonly small, weak, short and husky, noticed 

 only when the animal rises, drinks cold water, goes out to the 

 cold air, or eats dusty or fibrous fodder, and is usually attended 

 by arching of the back, extension of the head, opening of the 

 mouth and protrusion of the tongue. For weeks there may be 

 no indication of constitutional disorder, appetite, rumination, 

 milking, and other functions appearing to be normal. Driving 

 the animal may unduly accelerate the breathing, and a careful 

 auscultation may detect an unusually loud blowing sound behind 

 the middle of the shoulder, a mucous rale, or a wheeze. In some 

 cases the disease never advances farther, the trouble subsides and 

 the subject is thereafter immune. Cases of this kind occurring 



