Etiology. 409 



in the etiology of the disease has however not been definitely estab- 

 lished. Nocard found in the pseudo-membranes of the larynx and the 

 nasal cavity, bacilli resembling the bacteria of hemorrhagic septicemia. 



The etiology has been more closely studied by Leclainche, and the 

 results of his investigations may be summed up as follows : A virulent 

 variety of the colon bacillus may be demonstrated in the intestinal canal, 

 in the lymph glands of the mesentery, sometimes also on the nasal mucous 

 membrane, in the horn core and in the sub-lingual glands. This organ- 

 ism produces very poisonous toxins in bouillon culture, especially for 

 young cattle. Two cc. of a 15-day old bouillon culture injected intra- 

 venously or 10 cc. injected subcutaneously into a calf about nine months 

 old, produces after a few minutes severe symptoms of poisoning (restless- 

 ness, trembling, rising temperature, colic, serous discharge from the nose, 

 and lachrymation), which after 24 to 48 hours gradually disappears. 

 Intravenous injection of 10 to 40 cc. of a one-day old culture produces 

 diarrhea, nasal discharge, and salivation, whereupon the animal dies 

 in from 5 to 6 hours, and on autopsy all mucous membranes are found 

 markedly reddened. Feeding of one liter of the culture causes only 

 a passing diarrhea. 



Leclainche considers these symptoms and changes as identical with 

 those which are observed in the early stages of the disease, and believes 

 that the bacteria which multiply rapidly in the intestinal canal migrate 

 into the neighboring lymph glands and produce toxins, which after 

 absorption produce a general intoxication and catarrhal hyperemia of 

 the mucous membranes, whereupon streptococci and other pyogenic bac- 

 teria subsequently cause suppuration and necrosis in these tissues. In- 

 asmuch however as Leclainche did not succeed in producing the disease 

 in its typical form, and as the observed symptoms of intoxication may 

 be brought on in a very similar manner by the inoculation of cultures 

 of other pathogenic bacteria, and as the virulent coli bacteria may also 

 multiply subsequently in the intestinal canal and later migrate into 

 the lymph glands, the conclusions drawn from the above investigation 

 must for the present be accepted with reservations. 



The nature and method of the natural infection is not yet 

 known accurately. The experience that the disease occurs 

 mostly, although not exclusively, in poorly constructed, low 

 and dark, badly ventilated stables, with unclean floors, appears 

 to indicate that the virus propagates on the contaminated 

 floors of such stables, and probably also in stable filth. From 

 such places it reaches the digestive tract of the animal with 

 the food or drinking water. In rare instances animals in pas- 

 ture may also become affected, these cases however, are fre- 

 quently associated with bad, polluted drinking water. 



The disease appears to be non-contagious. Experiments 

 of transmitting the disease by inoculation Avith the nasal secre- 

 tions of affected animals were without results (Brusasco, Esser, 

 Lotzer). Furthermore, animals which stand next to the af- 

 fected cattle do not become affected in spite of the very close 

 contact. If the disease spreads in a stable, or if it appears 

 at the same time in various places in a township or locality, 

 this cannot be attributed to its contagiousness, but rather to 

 the simultaneous influences of a common local cause. Instances 

 are recorded in which the disease appears annually in certain 



