Studies of Johne's Disease in Canada: XI. Complement-Fixation Titres and Blood Cell Picture.

Complement-fixation titres and haemograms were determined monthly during a period of approximately one year for nine cattle with Johne's disease. Three of four experimentally infected animals died during the interval or shortly afterwards; all three developed high complement-fixing titres with Johne's bacillus antigen. The experimentally infected animal that survived was serologically reactive for a few months, then became negative. One of the naturally infected cows exhibited a relatively high complement-fixing titre throughout but the other four were serologically negative or occasionally weekly reactive. All nine cattle showed a variable degree of neutrophilia and lymphopaenia but an absolute eosinopaenia was observed only in the three that died.