LECTURE XX 

 DISINFECTION 



Purpose. — In veterinary practice, disinfection is intended to 

 check the spread of infectious diseases, and to protect animals 

 already diseased from further infection, by killing the causative 

 microorganisms or by rendering them avirulent. 



Sources of infection. — In any process of disinfection it is 

 important to know the nature of the infecting germ and the 

 sources from which it comes. Germs of diseases are spread in 

 many ways; for instance by the manure or body fluids of sick 

 animals, by soiled water or food, or by any other contaminated 

 matter. Air may be contaminated from the skin or lungs of 

 diseased animals, for example by the coughing of a tuberculous 

 cow. The soil may be contaminated by the burial of diseased 

 animals or by the deposit of any infectious material upon the 

 surface. In such case, germs may be washed to ponds, sluggish 

 streams, or shallow wells, contaminating the water. Hides, 

 offal, and even the hair of a diseased animal, may be the means 

 of spreading disease, as in case of animals which have died of 

 anthrax. 



Diseases are often spread by ' ' carriers, ' ' for example, glanders 

 of horses or tuberculosis of cattle, i.e., by an animal which does 

 not show the disease. 



Thoroughness. — Disinfection is not reliable and should not be 

 depended upon unless done most thoroughly. To illustrate, a 

 stable must first be thoroughly cleaned of manure, litter and 

 cobwebs. Scrubbing is often necessary before the disinfectant 

 can be effectively applied. A small yard may be disinfected by 

 burning straw on it, or by removing the earth to a depth of at 

 least six inches and replacing it with fresh earth. Paved floor- 

 ing may be disinfected by burning over it any inflammable ma- 

 terial. Cracks should be disinfected by the free use of corrosive 

 sublimate solution. Pood which may have been contaminated 

 should ordinarily be destroyed, but in some cases it may be 

 given to nonsusceptible animals. Drinking places, currycombs, 



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