We’ve all heard the statistics about an aging America. The elderly represent the fastest growing-proportion of the U.S. population. In recent years horses have experienced a similar population shift.

A large portion of the equine population (about 15%) is composed of horses older than 20 and, even at this age, many remain actively involved in equestrian sports, reproduction, or as companions. Thus, further understanding of geriatric horses’ immune systems has become increasingly important to preserve good health and quality of life through their golden years.

A goal of the immunology research program at the University of Kentucky Gluck Equine Research Center is to understand how age affects the geriatric horse’s immune response to vaccination, particularly the equine influenza vaccine.

Previous studies have shown the immune response to inactivated equine influenza virus vaccines decreases with age; however, it remains unknown whether aging has an impact on vaccine efficacy. Because alternative vaccination approaches may prove more efficacious in aged horses, a vaccine/challenge study was recently performed at the Gluck Center using a canarypox recombinant virus-vectored vaccine. This live vaccine has limited replication and therefore mimics that of a natural infection, which is expected to induce a more significant and complete stimulation of the immune response compared to killed vaccines