CHEONIC BACTEEIAL DYSENTERY. 499 



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. 



SymptoTThs. — 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 mus- 

 cular 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 are out of all proportion to the severity of the symptoms 

 manifested. The disease appears to start in the small intestines, es- 

 pecially 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 

 or inside lining membrane is markedly wrinkled or corrugated, 

 showing large, coarse folds with more or less reddening or hemor- 

 rhagic patches or spots on the summits of the ridges, especially 

 noticeable in the large intestines. The mesenteric lymph glands are 

 usually somewhat enlarged and appear watery on section. The other 

 organs do not appear to be affected except from the anemia present 

 in the later stages of the disease. 



Differential diagnosis. — The principal disease with which bacterial 

 dysentery may be confused is tuberculosis, but the application of the 

 tuberculin test will readily diagnose the latter disease, while no reac- 

 tion will be noted in case the injected animal is suffering with the 

 former affection. The disease may also be mistaken for the parasitic 

 affections resulting from stomach worms (verminous gastritis) and 

 intestinal parasites, especially uncinariasis, but a microscopic exami- 



