374 DISEASES OF CATTLE. 



readily and accurately ascertainable by the clinical thermometer. (See 

 Plate in, 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 secretion, and general dullness are 

 symptoms quite invariably present in most infectious diseases. 



Secondary diseases or complications may arise during the course of 

 infectious diseases 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. But it may be worse than useless for those not yet in- 

 fected. 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 

 infectious diseases are disseminated. 



With some cattle diseases, such as anthrax, black quarter, and pleuro- 

 pueumonia, 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 mal- 

 adies, 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 

 disease is likely to run a chronic course, as in tuberculosis. The next 

 important step is to separate the well from the sick by placing the 



