ALTERATIONS IN BLOOD LYMPHOCYTE SUBPOPULATIONS AND HEMATOLOGIC VALUESIN NEONATAL CALVES AFTER ADMINISTRATION OF A COMBINATION OF MULTIPLE-ANTIGEN VACCINES

Objective-To evaluate alterations in lymphocyte subpopulations, CBC re sults, and clinical signs in neonatal carves inoculated with 3 commerc ially available proprietary multiple-antigen vaccines containing known quantities of endotoxin. Design-Prospective, randomized controlled fi eld trial. Animals-36 healthy Holstein heifer calves between 3 and 31 days old. Procedure-Vaccines were administered to 18 calves according to label instructions, except for the recommended age of administratio n. The 18 other calves served as unvaccinated controls. Two weeks afte r entry into the study, carves were given secondary doses of the same vaccines. Calves in both groups were examined and blood samples were c ollected for determination of lymphocyte subpopulations and hematologi cal parameters once daily for 5 days beginning on the day that both th e primary and the secondary vaccinations were given. Lymphocyte subpop ulations, including BoCD2(+), BoCD4(+), BoCD8(+), B cells, and gamma/d elta T cells, were determined by use of flow cytometry, using monoclon al antibodies as markers. Results-Vaccinated calves did not develop cl inical signs of illness. There were no significant differences in abso lute numbers of lymphocyte subpopulations between vaccinated and unvac cinated calves. Vaccinated carves had significantly higher rectal temp eratures, total WBC counts, and absolute neutrophil counts than did co ntrol calves. These differences persisted for 3 to 4 days after vaccin ation. Clinical Implications-findings confirm empirical observations t hat vaccination with multiple products at the same time may induce evi dence of an inflammatory response in most calves. Additional research is indicated to further evaluate the safety of using multiple vaccines simultaneously.