Immunologic and physiologic responses of calves inoculated with potassium thiocyanate extract of Pasteurella multocida type A.

Inoculation of calves with potassium thiocyanate (KSCN) extract of Pasteurella multocida type A in saline-tris buffer or in Freund's incomplete adjuvant or modified Freund's incomplete adjuvant resulted in the elicitation of agglutinating, hemagglutinating, bactericidal and homocytotropic antibodies. The antibody response was significantly (P = 0.05) higher in calves inoculated with the KSCN extract in either adjuvant than in those inoculated with the extract in saline-tris buffer. Hemagglutination also was observed if the KSCN extract of P hemolytica was used for sensitizing the tanned sheep red blood cells. Further, calf anti-P multocida extract antisera also was bactericidal to P hemolytica. The KSCN extract of P multocida was found to be nontoxic to calves at 2 doses tested, as judged by an evaluation of total and differential leukocyte counts, body temperature, and pulse rates at various intervals after inoculation.