360 DISEASES OF CATTLE. 



of the animal, and this is readily and accurately ascertainable by 

 the clinical thermometer. (See PL III, fig. 1.) The other symptoms 

 are variable and depend upon the particular organ or organs most 

 implicated. Loss of appetite, cessation of rumination and milk secre- 

 tion, and general dullness are symptoms quite invariably present in 

 most infectious diseases. 



During the course of infectious diseases secondary diseases or com- 

 plications may arise which are largely due to bacteria other than those 

 producing the original malady. These complications are often so 

 severe as to become fatal. In general it may be stated that they are 

 due to filthy surroundings, and hence cleanliness may become an 

 important aid to recovery. 



The treatment of infectious diseases is given under each malady so 

 far as this is allowable or advisable. These diseases are not, as a rule, 

 amenable to treatment. When the symptoms have once appeared the 

 disease is apt to run its course in spite of treatment, and, if it is one 

 from which animals usually recover, all that can be done is to put 

 them into the most favorable surroundings. Many infectious diseases 

 lead sooner or later to death, and treatment is useless so far as the 

 sick are concerned, and it may be worse than useless for those not 

 yet infected. All animals suffering with infectious diseases are a 

 menace to all others more or less directly . They represent for the time 

 being manufactories of disease germs, and they are giving them off 

 more or less abundantly during the period of disease. They may 

 infect others directly or they may scatter the virus about, and the 

 surroundings may become a future source of infection for healthy 

 animals. This leads us to the subject of prevention as the most 

 important of all which claim our attention. In this place only a few 

 general remarks will suffice to bring the subject before the reader. 



The most important thing is to keep disease away from a herd or 

 farm. To do this all sick or suspicious animals should be avoided. 

 A grave form of disease may be introduced by apparently mild or 

 trivial cases brought in from without. It is generally conceded that 

 continual change and movement-of animals are the most potent means 

 by which infections diseases are disseminated. 



With some cattle diseases, such as anthrax, rinderpest, and pleuro- 

 pneumonia, preventive inoculation is resorted to in some countries. 

 This may be desirable when certain diseases have become stationary 

 in any locality, so that eradication is impossible. It should not be 

 practiced in territories where a given disease may still be extirpated 

 by ordinary precautions. Preventive inoculation is applicable to only 

 a few maladies, and therefore its aid in the control of diseases is a 

 limited one. 



When an infectious disease has gained foothold in a herd the course 

 to be pursued in getting rid of it will depend upon the nature of the 

 malady. A good rule is to kill diseased animals, especially when the 



