Aim: In this study on guinea pigs, the relationships between neutralizing antibody titers produced by the addition of powder of Horse Chestnut seed and powder of Mistletoe dried leaves to the vaccines against Foot- and- Mouth Disease (FMD) were investigated and Quasi-Least Squares Regression (QLS) method in data analysis was introduced for the veterinary vaccine studies.

Materials and Methods: The experimental FMD vaccines were administered to three groups by subcutaneous route. Whether the neutralizing antibody titer levels (NATL) in the three groups were different according to the homologuos virus neutralization test (VNT) was statistically analyzed. Blood samples were taken from the animals to measure NATL generated in animals as a result of vaccination. These blood samples were taken under general anaesthesia, six times after vaccination (7, 14, 28, 60, 120 and 270 days), NATL measurements were made. Analyzes on the longitudinal data obtained were performed with QLS and Generalized Estimation Equations (GEE) methods.

Results: It was observed that the measurement times (days) in NATL variable (response variable) was not significant in both QLS and GEE methods (p >0.05). Similarly, the group effect was not found to be significant in both methods (p> 0.05).

Conclusion: The fact that the group variable effect on NATL variable was not found to be statistically significant means that the effects of the addition of powder of Horse Chestnut seed and Mistletoe dried leaves to the FMD vaccines on the groups were not different.