624 COMMUNICABLE DISEASES OF LABORATORY ANIMALS 



McKee.' These workers found in Baltimore that certain fatal cases of acute snufiEles 

 were invariably associated with Bad. bronchisepticum; the Pasteurella organism could 

 not be demonstrated. Since, however, the same organism has been isolated from 

 respiratory infections of dogs, guinea pigs, and white rats, its etiological relationship 

 to acute and chronic snuffles, pleuropneumonia, and septicemia remains obscure. 



In subjecting the respiratory infections of rabbits to a detailed experimental and 

 carefully controlled study on specially bred laboratory rabbits with a known history 

 and also on the stock of several commercial rabbitries in New York State, Webster 

 and Burn have shown that Bad. lepisepticum is the primary etiological factor in 

 snuffles and its complications. From personal experience extending over many years, 

 the writer finds himself in agreement with the main observations and conclusions re- 

 ported by Webster^ in a series of valuable papers. 



An examination of the nasal secretion of a rabbit population in which snuffles 

 is frecjuently encountered shows the following bacteria in the order of their frequency: 

 Micrococcus catarrhalis group, 80 per cent; Bad. lepisepticum, 70 to 100 per cent; gram 

 negative cocci and Bad. bronchisepticum, 40 per cent; staphylococci, streptococci, 

 and various intestinal bacilli, 10 per cent. Tanaka^ arranges the varieties in the fol- 

 lowing order: Micrococcus catarrhalis, Staphylococcus albus, gram negative cocci, 

 Bad. lepisepticum, unidentified organisms. Bad. bronchisepticum, streptococci. In 

 this connection it is important to emphasize that the technique given by Webster 

 must be rigidly followed. A 5 per cent deiibrinated rabbit-blood agar (pH 7.5) poured 

 shortly before use will give dependable information. The onset of spontaneous snuffles 

 is preceded by the appearance in the nasal passages of Bad. lepisepticum, and during 

 the active stages this organism invariably predominates. Recovery is accompanied 

 by a diminution, the final disappearance from the nasal passages, or the persistence 

 in the paranasal sinuses. The application of a drop of i per cent silver nitrate solu- 

 tion (Freund)'* or a 0.1-0.3 per cent brilliant-green solution (Bull and Bailey)^ may 

 provoke a relapse of clinical snuffles; even pneumococci and Bad. lepisepticum may be 

 isolated in almost pure culture from the lesions. Various other experimental pro- 

 cedures (as, for example, the injection of putrid material [Koch and Gafifky]),'' the 

 inoculations of vaccines, toxins, Treponema pallidum, tumor specimens, operations, 

 bleeding, etc. (Webster,7Tanaka), may impair the resistance to spontaneous snuffles. 



Without extended infection experiments conducted on rabbits bred with a view 

 to protection from exposure to snuffles in any of its stages, Webster would have been 

 unable to correlate the various clinical and anatomical manifestations which are 

 controlled by the susceptibility of the rabbits and the pathogenicity or the virulence 

 of the different strains of Bad. lepisepticum. Among the many factors which ap- 

 parently affect the "natural" resistance in a rabbit population the following are in all 



1 Bull, C. G., and McKee, C. M.: Am. J. Hyg., 5, 530. 1925. 



2 Webster, L. T.: /. Exper. Med., 39. 837, 843, 857. 1924; 40, 109, 117. 1924; 42, i. 1925; 43, 

 .■^55, 573- 1926. 



sTanaka, A.: loc. cit. ^ Freund, R.: loc. cit. 



5 Bull, C. G., and Bailey, G. H.: Proc. Soc. Exper. Biol. &- Med., 24, 183. 1926. 

 '^Koch, R., and Gaffky, G.: Mitt. d. kaiserl. Gesundhcitsamtc, i, 80. 1881. 

 'Webster, L. T.: J. Exper. Med., 40, iii. 1924. 



