Symptoms. 



47 



of the diseased muscles numerous clostrydian forms are seen, and if the course of the 

 disease is not acute the bacilli will be found to contain spores at the time of death 

 and still more 24 to 48 hours later. 



Miiller recommends to submit for bacteriological examination pieces of muscles 

 covered with salt, because the decaying process is arrested l)y the salt and the black- 

 leg bacilli are stimulated to a rapid formation of clostrydian forms and spores. 



The gases formed in the crepitant swellings have not always the same com- 

 position; according to Eoux, they consist of carbonic acid and hydrogen in equal 

 proportions, while Tappeiner 's chemical analysis shows 13.15% of carbonic acid, 

 76.51% of hydrogen, and 10.34% of nitrogen. 



Symptoms. The period of incubation of the disease is 

 generally 3 days, although in exceptional cases it may be more, 

 but does not, however, exceed 5 days. 



In cattle the disease starts with sudden febrile symptoms ; 

 the animals stop eating, grazing and ruminating, the tempera- 

 ture rising in a few hours to 41-42° C. (Fig. 16.) In many 

 cases, however, the disease seems to progress with a moderate 

 temperature or without 

 fever (Schiitt & Warring- 

 holz, Steinbriick). In graz- 

 ing animals lameness or 

 stiff dragging of an extrem- 

 ity is also frequently ob- 

 served. 



Shortly thereafter may 

 be seen the characteristic 

 blackleg sw^elling, particu- 

 larly in portions of the body 

 with thick layers of muscle. 

 Most frequently they appear 

 on the upper leg, on the 

 buttocks, in the region of 

 the loin, on the shoulder, 

 chest or neck (in exceptional 

 cases also in the submaxil- 

 lary space [Fig. 17], on the 

 tongue or on the throat), while they never appear below 

 the carpal or tarsal joints or on the tail. At one of 

 the above named places a distinctly bordered or diffuse 

 swelling of irregular shape develops rapidly, which, from the 

 beginning, is hot and painful, later becoming cold and torpid 

 in the center, so that the animal finally does not feel pain on 

 touch or when an incision is made. The skin over the swelling 

 is dry, stiff, dark colored, incidentally black and parchment-like, 

 and in exceptional cases also necrotic. On palpating or pressing 

 the tumor a peculiar crepitation is observed, while percussion 

 brings forth a pronounced tympanitic sound. If the swelling 

 is cut at the beginning of the disease, dark red blood, later a 

 dirty red, foamy and singularly sweet smelling liquid "will be 

 discharged from the w^ound. The tissues surrounding the tumor 

 are edematously infiltrated. The lymph glands are swollen 

 and may be felt under the skin as firm knots the size of apples. 



Fig. 16. Fever curve in blackleg. The 



animal became affected on the 



previous evening. 



