CHAPTER XXJXV. 



A LOCAL EQUINE DISEASE AND A BACILLUS OF THE SUBTILIS 



GROUP. 



IN the neighborhood of Lake Winnebago and in other places in 

 Wisconsin a disease among horses characterized by a rather rapid 

 onset has been frequently observed in the late summer or early fall. 

 The animal appears to be perfectly well in the evening, the following 

 morning it refuses to eat or drink, inclines the head downward, 

 breathes very rapidly, has a rapid pulse of about 80, and a temperature 

 ranging from 104 to 107 F. The stools are first loose, and a profuse 

 diarrhea, which reaches its maximum in about three days, develops 

 rapidly. Sometimes the bowels are not loose but rather constipated, 

 and then pulmonary symptoms develop. The animals so affected 

 generally die. 



The author, in conjunction with Dr. O. N. Johnson, of Appleton, 

 Wis., in August, 1908, examined bacteriologically a number of cases of 

 this affection occurring in Dr. Johnson's practice. Blood was obtained 

 from the jugular vein of sick animals under aseptic precautions in 

 8 cases and immediately distributed to culture tubes and flasks. In 5 

 cases an identical organism was obtained. It was a rather large, lively 

 motile, Gram-positive bacillus, which grew best at room temperatures, 

 less rapidly at the incubator temperature (37 C.). On agar it 

 formed a white, moist, shining, rather rapidly spreading growth; 

 gelatin in stick cultures was rapidly liquefied, with the formation of a 

 funnel-shaped zone of liquefaction; it produced acid in litmus milk 

 and coagulated it after seventy-two hours; on glucose agar it did not 

 grow as well as in plain agar along the stab, but grew well on the 

 surface and did not produce any gas. In bouillon turbidity it was 

 produced rapidly, but no pellicle was formed on the surface. Spore 

 formation occurred in various media after twenty-four hours' incu- 

 bation at 37 C. One of the stems examined had not coagulated milk 

 after seventy-two hours and another stem formed a dry, hard pellicle 

 on bouillon. In other respects the action of the five stems was identical. 

 On the whole, the organism appeared to be a member of the subtilis 

 group, but it seems hardly possible that it was an outside contami- 

 nation, as it developed in the blood inoculations from five out of eight 

 horses examined. 



Emulsions of the organism raised on agar slants and prepared 

 with physiologic salt solution were injected intraperitoneally into a 

 number of guinea-pigs. During the first three or four days no visible 



