6o8 COMMUNICABLE DISEASES OF LABORATORY ANIMALS 



vaccination, and the host susceptibility which may be influenced by hereditary and 

 environmental factors, diets, etc. An extensive literature has already accumulated, 

 and it is impossible to do justice to the subject in this brief chapter. Many important 

 data must be omitted, and the reader can only expect a presentation of the essential 

 facts. Then again a number of infections have not been studied with the care they 

 deserve and therefore the conclusions must of necessity be brief and noncommittal. 

 This rather one-sided account must also ignore the various deficiency diseases, such 

 as scurvy, which not infrequently reduce a poorly managed laboratory stock. Particu- 

 lar attention will be paid to the diseases of guinea pigs, rabbits, mice, and rats, and 

 then primarily to those infections which are due to bacterial agents. The presenta- 

 tion considers the various diseases in the order of their importance. Those interested 

 in the parasitic invasions will find some information in a brief summary by the writer.' 



DISEASES OF THE GUINEA PIG 



The guinea pig is probably more frequently used for bacteriological studies than 

 any other animal since it is particularly susceptible to infections with human and 

 animal pathogenic micro-organisms. Aside from the artificially produced pathological 

 processes, the rodent is however liable to numerous spontaneous communicable 

 diseases. Everybody who experiments with this animal should be familiar with the 

 clinical and preferably the postmortem findings, since not infrequently morbid lesions 

 are encountered which can only be properly diagnosed when the pathology and the 

 bacteriology of the spontaneous infections are fully recognized. Several years ago 

 Holman^ and more recently Raebiger and Lerche^ brought together in a concise form 

 the pathologic-anatomical findings of the diseases of guinea pigs with special refer- 

 ence to their etiology. The excellent summaries contain an abundance of important 

 data which the writer will correlate with a number of recent contributions and his 

 personal experiences. 



The wavelike outbreaks which may carry off in a short time a large number of 

 animals are due to one of two types of infections: (i) a disease to which Eberth^ gave 

 in 1885 the designation "bacillary pseudotuberculosis"; (2) septicemias or respira- 

 tory diseases due to a pneumococcus, a pasteurella organism, or the Friedlander's 

 bacillus. Probably the most important one is the pseudotuberculosis caused by repre- 

 sentatives of the paratyphoid-enteritis group. To avoid confusion, this communicable 

 disease should be designated as "paratyphoid" in order to distinguish it from those 

 infectious processes which are due to the Bacillus pseudotuberculosis {rodentium) 

 Pfeififer. 



PARATYPHOm 



This disease was recognized as early as 1884, and a good description of a small 

 epidemic which attacked pregnant females as well as newborn animals was given by 



'Meyer, K. F.: Practical Bacteriology, Medical Zoology and Immunology, "University of Cali- 

 fornia Syllabus Series," No. 179, pp. 52-57. Berkeley: University of California Press, 1925. 

 ^Holman, W. L.: /. Med. Research, 35, 151. 1916. 



3 Raebiger, M., and Lerche, P.: Ergebn. d. allg. Path. u. Anat., Abt. II, 21, 686. 1926. 



4 Eberth, C. J.: Virchow's Arch. f. path. Anat., 100, 15. 1885; Pertik, O.: Ergebn. d. allg. Path, 

 u. Anat., Abt. II, 8, n8. 1904. 



