614 DISEASES OF CATTLE. 



The former has proposed the name chronic bacterial dysentery for 

 this affection, and it has a4so been termed Johne's disease, chronic 

 bacterial enteritis, chronic hypertrophic enteritis, and chronic bovine 

 pseudotuberculosis enteritis by various European investigators. The 

 disease was first studied in 1895 by Johne and Frothingham in Dres- 

 den, but they were inclined to attribute the cause of the peculiar 

 lesions of enteritis which they observed to the avian tubercle bacillus. 

 In 1904 Markus reported this disease in Holland, and subsequently 

 it was observed in Belgium, Switzerland, Denmark, and Great 

 Britain. 



Cause. — The bacillus, which has been invariably demonstrated in 

 the intestinal lesions and mesenteric lymph glands in this disease, is 

 a rod about 2 to 3 microns long and 0.5 micron wide. It stains more 

 or less irregularly like the tubercle bacillus, and moreover the simi- 

 larity goes further in that the organism is also strongly acid-fast, 

 which facts led Johne and Frothingham to surmise that the disease 

 was caused by avian tubercle bacilli. However, it has now been 

 plainly demonstrated that the bacillus of chronic bacterial dysentery 

 is readily distinguished from the latter organisms, for while it resem- 

 bles the tubercle bacillus in form and staining qualities, no one has 

 succeeded in growing it in culture media or in reproducing the dis- 

 ease by injecting experiment animals. 



Symptoms. — Probably the first symptom noticed is that the animal 

 is losing condition despite the fact that its appetite is good and the 

 food nourishing. This is soon followed by a diarrhea which, while 

 moderate at first, soon becomes excessive and may be either irregular 

 or persistent, the feces being of the consistency of molasses and passed 

 frequently. In the meantime the hair becomes dry and harsh and 

 the animal falls off considerably in weight. The temperature, how- 

 ever, remains about normal. The appetite does not seem to be greatly 

 impaired until the last few weeks of life, but nevertheless emaciation 

 continues, the animal becomes more and more anemic, great muscu- 

 lar weakness and exhaustion are manifested, and death follows, 

 apparently as the result of the persistent diarrhea and great emacia- 

 tion. The disease may continue for four or five weeks or may last 

 for a year or even longer before death intervenes. 



Lesions. — The lesions observed on post-mortem are remarkably 

 slight and out of all proportion to the severity of the symptoms mani- 

 fested. The disease appears to start in the small intestines, especially 

 in the lower portion, where the lesions are usually the most marked, 

 but it also involves the large intestines, including the rectum. The 

 mucous membrane may alone be affected, although usually in the 

 long-standing cases the submucosa is also invaded and the entire 

 intestinal wall is then much thicker than normal and the tissue 

 infiltrated with an inflammatory exudate. The mucous membrane 



