EIGHTH ANNUAL YEAR BOOK— PART YI. 237 



spread of diseases among animals in this country has met with the 

 greatest opposition among the owners of these animals. I am led to be- 

 lieve that it is the immediate financial losses that cause this opposition, 

 and in nearly every case we may expect a yearly visitation of the divest- 

 ing plague and have perpetually exemplified the painful results of a 

 penny wise and pound foolish policy. How much better would it be if so 

 many of us were not so blind and could see that it was more economical 

 to isolate, treat or destroy all animals diseased than to permit them to 

 remain as disturbing centers from which the disease may be spread. 



The causes of disease are simple or complicated, a single factor may 

 not in itself be sufficient to cause disease, but may, if associated with 

 another which would have been innocuous if acting alone. 



We classify causes into predisposing and exciting. Predisposing causes 

 are such as induce a condition of the system or particular organ, or group 

 of organs, which renders them especially susceptible to disease. This 

 may be characteristic of the race or genus of the animal, or hereditary 

 influences, previous disease in a tissue or organ leaves for the time an im- 

 pairment of structure which may become an essential predisposing cause. 



Exciting causes are the immediate factors in the causation of particular 

 diseases. Heat, if excessive and prolonged, exerts a direct influence on 

 the animal economy, and may become the direct cause of a number of 

 diseases. Cold is equally detrimental and when proper housing is not 

 provided for swine, chilling may take place, and pneumonia or pleurisy 

 result. This is especially true where large numbers are kept together 

 instead of having pens properly protected and large enough to hold twelve 

 or fifteen animals. 



The condition of the atmosphere, when charged with offensive gases 

 or the emenation from manure pits or other foul places, is often a direct 

 cause of disease. The emenations from manure pits are believed to be 

 healthy, even by some educated persons, probably it is the ammonia that 

 reminds them of smelling salts. The vitiated air reduces the resistance 

 of the body tissues by inducing a state in which the natural defences are 

 weakened, and an avenue for infection established. Foul air and over- 

 crowding are the prime factors in the production of disease, and it may be 

 truly said that "disease and health are in the direct proportion of foul 

 air and pure air." 



Darkness always deteriorates the general health and makes it possible 

 to have corners and other places for the accumulation of filth. Light is 

 invigorating, and it is also detrimental to the growth of germs. 



Hog cholera, swine plague, anthrax and tuberculosis of the infectious 

 diseases and various other parasitic affections of the digestive and 

 respiratory system may be transmitted through the medium of streams. 

 It is not an easy matter to indicate the impurities of water which produce 

 disease, aside from the use of very hard water, or one holding in sus- 

 pension large quantities of mud and filth. These act mechanically on the 

 digestive canal, and their results are easy of comprehension. Impure 

 water is not conducive to good health, and anything which detracts from 

 this in the highest obtainable degree is rendering the animal more prone 

 to suffer from disease. 



