With more horses living to a ripe old age than in the past, veterinarians have become incredibly well-versed in managing senior equids. But there are still some points that researchers are working to understand. For instance, exactly what impact does aging have on the immune system?

At the 2013 American Association of Equine Practitioners’ Convention, held Dec. 7-11 in Nashville, Tenn., Dianne McFarlane, DVM, PhD, Dipl. ACVIM, ABVP, associate professor in physiological sciences at Oklahoma State University Center for Veterinary Heath Science, reviewed what veterinarians know and what they’re still working to learn about immunosenescence in horses.

"Immunosenescence is the effects of aging on the immune system," McFarlane explained, but cautioned that there’s still not much published data on equine immunosenescence