Respiratory tract disease and mucosal colonization by Pasteurella haemolytica in transported cattle
Frank, G.H.; Briggs, R.E.; Loan, R.W.; Purdy, C.W.; Zehr, E.S.
American Journal of Veterinary Research 57(9): 1317-1320
1996
ISSN/ISBN: 0002-9645 PMID: 8874726 Document Number: 463101
Objectives: To follow incidence of Pasteurella haemolytica (PH) in the upper respiratory tract of healthy calves at the farm and through the marketing process, and to determine the effect of vaccination on PH colonization of the upper respiratory tract and on the incidence of respiratory tract disease (RTD). Animals: 2- to 5-month-old calves (n = 104) from 4 farms. Procedure: Calves were vaccinated with a killed PH serotype-1 product. Nasal secretion and tonsil wash specimens were cultured for PH, and serum antibody was measured by indirect hemagglutination. Calves with RTD were treated with tilmicosin phosphate. Results: At the feedyard, 73 calves had RTD. The incidence of RTD was significantly related to the farm of origin, and was inversely related to the PH serum titer at the farm, but was not influenced by vaccination. Isolations of PH serotype 1, however, were reduced by vaccination. The major serotypes of PH encountered were 1 and 6. Conclusion: Vaccination can reduce the frequency of colonization of the upper respiratory tract by PH.