The effect of age on serum antibody titers after rabies and influenza vaccination in healthy horses.

This research article investigates the effect of age on the immune response of horses to rabies and influenza vaccinations. It found that older horses have a lower increase in serum antibody response to vaccines compared to younger horses.

Objective of the Study

The main objective of the study was to determine if aged horses would respond differently to vaccination in terms of serum antibody response compared to younger adult horses. This is essential, given the increased proportion of geriatric horses in the equine population, and the currently limited information on their immune function.

Methodology

• Overall, 34 aged healthy horses, aged 20 years and above, and 29 younger adult horses aged between 4 and 12 years, were used in the study.
• All horses received vaccinations of killed rabies and influenza virus.
• A booster dose of either rabies or influenza vaccine was administered to each age group 4 weeks after the initial vaccination.
• Serum samples were collected at 0, 4, 8, and 24 weeks later.
• Different tests were performed to check the antibody subtypes and titers, including Rabies serum neutralization titers, equine influenza virus-specific antibodies, and single radial hemolysis (SRH) titers.

Results

• The serum antibody response to rabies was found to be similar in the two age groups at all timepoints.
• Aged horses had higher influenza-specific antibodies before vaccination compared to younger horses, however, they showed similar levels after vaccination.
• Younger horses demonstrated a significantly higher increase in antibody titers at all three timepoints post the first vaccination.
• Interestingly, there was no detectable serum IgG(T) observed at any timepoint.
• The booster vaccine had a noticeable effect on both rabies and influenza antibody titers.

Conclusions

The study concluded that aged, healthy horses generated a primary immune response to the killed rabies vaccine that was similar to that of younger adult horses. However, when it came to the influenza vaccine, aged horses had a noticeably reduced anamnestic response, which is the ability of the immune system to quickly and specifically recognize an antigen that the body has previously encountered and initiate a corresponding immune response.