PREVENTIVE MEDICINE 247 



All animals and man are susceptible to tetanus, but the disease 

 is more frequently encountered in equines, although, as mentioned 

 above, it is occasionally seen in the form of enzootics among lambs 

 and also among young pigs. Cattle and dogs are less susceptible, 

 and cases occur less commonly in these species. Fowls are very 

 resistant. 



The disease follows the inoculation of a wound with material 

 containing tetanus bacilli or their spores, and consequently soil, 

 manure, and stable dust are especially dangerous. It is before all 

 punctured or lacerated wounds which are liable to be complicated 

 by tetanus, and infection is favoured by the simultaneous presence 

 of other bacteria. 



Any wound which contains much necrotic tissue, decomposing 

 blood clot or pus will form an especially suitable nidus for the 

 development of the organism. 



The tetanus bacillus exerts its action through the medium of a 

 very powerful toxin, which is elaborated as the result of its growth. 

 In practice, cases of tetanus are noted to follow most frequently 

 certain injuries such as picked-up nail, pricks during shoeing, and 

 harness galls. Infection may also follow dental caries. The 

 shearing of sheep, castration, and docking of foals, lambs and 

 calves produce wounds which are not uncommonly followed by 

 tetanus. The application of the actual cautery leads to a certain 

 amount of necrosis, and a suitable site for the growth of the bacillus 

 may in this way be created. Parturition in the cow has been 

 followed by tetanus as the result of wounding of the genital 

 passages. 



When the disease arises as the result of a discoverable wound 

 it is sometimes spoken of as " traumatic tetanus " as opposed to 

 cases of so-called " ideopathic tetanus " in which a careful exami- 

 nation fails to reveal the point of infection. It is probable that 

 there is no such thing as " ideopathic tetanus," and in this con- 

 nection it must be remembered that infection may occur through 

 very minute abrasions, e.g., in the intestinal tract. 



The period of incubation may be set down at from about 3 days 

 to $ weeks. Hutyra and Marek* state " that in most cases in 

 horses symptoms appear from 1 to 2 weeks after infection." 

 Cadiot noted that of 38 cases in horses symptoms appeared in 28 

 between the 5th and 20th days. According to Hoffman, the period 

 of incubation of " parturition tetanus " in cows is 2 to 14 days, and 

 in rams and boars after castration, 8 to 14 days. Dieudonne has 

 reported 58 cases of tetanus following docking, in which the period 

 * Hutyra and Marek, Spec. Path., Vol. I., p. 449, Trans. 



