212 ANIMAL INOCULATION 



If internal organs are to be examined it is best to kill a 

 moribund animal than to wait for death, since after death, 

 and in severe infections even sometimes before, the tissues 

 are rapidly invaded by saprophytic bacteria from the ali- 

 mentary and respiratorj' tracts which complicate greatly 

 the isolation of the specific organism. Hence the search for 

 specific bacteria in carcasses or on organs several hours after 

 death is frequently negative. Animal inoculation with such 

 material is very often followed by sepsis or septicemia in a 

 few hours, so that the specific organism has no opportunity 

 to manifest itself. 



In securing material for cultures from internal organs it 

 is a good plan to burn the surface of the organ with a gas 

 or alcohol flame, or to sear it with a hot instrument to 

 kill surface organisms, then make the incision or puncture 

 through the burned area and secure material from the inte- 

 rior of the organ. Such punctures made with a stiff platinum 

 needle frequently give pure cultures of the organism sought. 

 Slides may be made from such material and culture media 

 inoculated at once 



Since a bacteriological diagnosis depends most commonly on 

 growing the organisms, it is evident that material sent for 

 examination must never be treated with an antiseptic or pre- 

 servative. If decomposition is to be feared the only safe pro- 

 cedure is to pack the material in ice and forward in this way. 



Tuberculous material from the parenchyma of internal 

 organs may be forwarded in a preservative (not formalin, 

 since this makes it very difficult to stain the bacteria) as in 

 this special case a very positive diagnosis may be made by 

 staining alone. Even here it is better to pack in ice in 

 order that the diagnosis by staining may be confirmed by 

 inoculating the living organisms into guinea-pigs. 



In the case of material from a rabid animal and many 

 protozoal diseases the rule against preservatives is not abso- 

 lute, since staining is a reliable diagnostic means. Even 

 in these cases it is often desirable to inoculate animals, 

 hence, as before stated, it is best to make it a uniform 

 practice to pack material for examination in ice and use no 

 preservatives. 



