INFECTIOUS ABORTION 



523 



2. BiLi^iNGS. The corn fodder disease in cattle and other farm 

 animals, with especial relation to contagious pleuro-pneumonia in 

 American beeves in England. Bulletins No. 22 and 23. Univ. of Neb. 

 Agric. Exper. Station, 1892. 



3. DB SCHWEINITZ. Chemical examination of cornstalks presum- 

 ably the cause of cornstalk disease in cattle. Bulletin No. 10, U. S. 

 Bureau of Animal Industry, 1896. 



4. Gamgee. Diseases of cattle in the United States. U. S. De- 

 partmemt of Agriculture, 1869. 



5. Mayo. Cattle poisoning by nitrate of potash. Bulletin No. 4g, 

 Kansas Agric. Exper. Station, 1895. 



6. Mayo. Cornstalk diseases in cattle. Ibid, 1896. 



7. Moore. An investigation into the nature, cau.se and means of 

 preventing the cornstalk disease (Toxemia Maidis) of cattle. Bulletin 

 No. 10, U. S . Bureau of Animal Industry, 1896. 



INFECTIOUS ABORTION. 



§ 411. Characterization. The disease or condition 

 known as infectious abortion consists in the expulsion of the 

 immature fetus, usually before it has sufficiently developed to 

 live after birth, by a large proportion of pregnant animals that 

 are kept together. Usually the abortion occurs in cattle be- 

 tween the fifth and eighth month of gestation. The disease 

 as described by European writers is characterized by certain 

 morbid changes in the uterine mucosa and fetal membranes. 

 American observers have not described these changes. In 

 cattle it usually affects the young cows. After two or three 

 consecutive abortions cows, as a rule, become immune to it. 

 Cows suffer most from this condition, although mares, ewes, 

 and other species are occasionally reported to be affected. 



In Norway infectious abortion is scheduled under the so- 

 called "milder contagious diseases." The owner is obliged to 

 report when such a disease appears in his herd, and he is not 

 allowed to bring such animals to fairs or cattle shows. 



§ 412. History. Abortions in epizootic form have been 

 recorded from very early times. Mascal, in 1859, gives direc- 



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