No. 7. DEPARTMENT OF AGRICULTURE. 18] 



possibility of the existence of rabies ; aud in sncli a case, tlie labora- 

 tory examination should be relied upon as well as in those cases in 

 which the history and autopsy findings witliout the syiuptoms fail 

 to be conclusive. 



THE USUAL HISTORY 



The dog has for centuries l)eeii Known to be the real carrier and most 

 frequently afflicted of all the warm blooded animals. The often re- 

 jieated statement credited to Aristotle, who lived from 284 to 322 B. 

 C, "Of these, Lyssa (rabies) causes mania, and whatever is bitten, 

 of these bitten go mad except man"^ is taken as evidence that rabies 

 existed before the beginning of the Christian era, and strengthens 

 the belief that dogs suffered from madness. Unfortunately, the ob- 

 servations of Aristotle were not thorough enough to note the trans- 

 mission of the disease from dogs to man. In Russia, the wolves are 

 credited with harboring and spreading the disease. The dog and 

 wolf are not any more susceptible to the disease than are other warm 

 blooded animals, but the dog through freedom allowed him and his 

 habit of exchanging greetings and joining in combat with his kind 

 and other species, exposes himself to the chances of infection. The 

 popular belief that dogs are more apt to go mad or develop rabies 

 in Summer, particularly during the so-called "dog days" — the time of 

 the year from July 3, to August 11, when the "dog star," Sirus, is 

 above the horizon with the sun — is not corroborated in referring to 

 Table No. 1, in which it may be seen that during July and August 

 the number of heads of animals suspected of having rabies received 

 at the laboratory was not as large as in many of the other months 

 during 1900 to 1909, inclusive. 



The largest number of heads were received during the months of 

 November and December. As it is a fact that dogs do mingle more in 

 warm weather, therefore, they are moi'e exposed and should infection 

 take place, with its subsequent period of incubation of 4-8 weeks be- 

 fore symptoms develop, the appaient inci'ease in the number of heads 

 during the months of November and December may be accounted for. 

 With the spread and increasing prevalence of rabies, it must be 

 recognized that dogs permitted to run at large, even for short periods 

 at a time, may while at liberty, be exposed to a rabid animal. The 

 owner of a suspected animal will not infrequently insist that this 

 or that animal was not exposed ; but in almost every instance, some 

 loophole in the confinement of the closest of pets can be discovered. 

 It is well kuown how eagerly doos, seldom ]>ermitted to run at large, 

 join other dogs when granted that freedom, thereby increasing the 

 chances of exposure in arousing a passing or sulking rabid dog. In 

 gathering the history, an attem]>t should be made to find out the day 

 of exposuie or time of infection. Not infrequently, as proof of ex- 

 posure, a healing Avound, the result of a bite may be detected on 

 some part of the body. 



The period of incubation of rabies in the domestic animals in- 

 cluding man is usually within the folknving number of days: 



Man — 14 to 90 days. 



Dogs — 14 to fiO days, authentic exception 3(>5 days (3) 



Cats— 14 to 60 days. 



Cows— 14 to 80 da vs. 



