426 DISEASES OF CATTLE. 



the spread or recurrence of this disease are equally applicable to black- 

 quarter, and hence do not need to be repeated here. Furthermore, there 

 is practically no danger of a transmission of this disease from one 

 animal to another, since it is contracted on the pastures from the ground 

 and in stables from the food. 



Before closing this brief account of the disease it may be interest- 

 ing to mention the efforts which have been made in the direction of 

 preventive inoculation. Three French veterinarians, Arloing, Oorne- 

 vin, and Thomas, have devised a method of inoculation which produces 

 immunity from subsequent attacks. The method has undergone various 

 modifications in their hands, and at present consists in an inoculation 

 of weakened virus beneath the skin of the tail. The virus is prepared 

 as follows : 



The muscular tissue from the site of the swelling is dried rapidly 

 and then mixed with two parts of water. The mixture is allowed to 

 dry in ovens raised to a certain temperature. Two vaccines are pre- 

 pared, a first or weaker vaccine which has been exposed to a dry heat 

 of 212 F. for six hours, and a second or stronger vaccine exposed to 

 the lower temperature of 185 F. for the same length of time. Of each 

 of these dried vaccines a small quantity is ground up with water and 

 injected under the skin of the tail. The second vaccine is injected ten 

 days after the first. Those who have tried this method regard it as 

 safe and valuable in those districts where the disease annually recurs. 



MALIGNANT CATARRH. 



Malignant catarrh' or infectious catarrhal fever may be defined as an 

 acute infectious disease of cattle, in which the respiratory and the diges- 

 tive organs are involved in the disease. The cause of this affection has 

 not as yet been determined, although the general belief among author- 

 ities is that it is a disease due to microorganisms, perhaps belonging 

 to the bacteria. It is not, strictly speaking, a contagious disease, like 

 rinderpest or foot-and-mouth disease, for example, and hence it does not 

 appear in extensive outbreaks like these, but chiefly in isolated or con- 

 secutive cases. The predisposing causes are but little known, and vari- 

 ous theories have been offered to explain observed facts. One author 

 claims that the infection may arise in stables not kept well cleaned and 

 dry. That it may recur year after year on the same farm or in the same 

 locality has been frequently noticed by veterinarians in Europe. Noth- 

 ing positive is known whether the conditions of the soil have any bear- 

 ing on this disease, as they undoubtedly have in anthrax, for instance, 

 for it seems to exist both in valleys and in elevated regions. Fortu- 

 nately 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. 



Synqttoms. Malignant catarrh attacks by preference young and well- 

 nourished animals in the spring of the year. According to authorities 



