Nutritional immunology for the geriatric horse

Abstract Text:

Over the past century, improvements in health care and advancements in science and medicine have extended the average lifespan of humans and companion animals, including horses.  We are now facing new challenges with the paradox of an older horse population with increased longevity and the potential of increased age-associated diseases.  One of the most recognized consequences of aging is a decline in function of the immune system.  Two main terms that characterizes a declining immune system of the old horse are immunosenescence and inflamm-aging.  Immunosenescence in the aged individual is characterized by changes in various aspects of cellular and humoral immunity, in particular, a decline in lymphoid cell numbers and function. It has been well-documented that the aged, including horses, have increased susceptibility to and prolonged recovery from infectious disease, poor vaccine responses, and increased incidence of cancers.  Somewhat paradoxically, advanced age is also associated with increased production of pro-inflammatory cytokines and other inflammatory mediators, a phenomenon termed inflamm-aging.  Inflamm-aging predicts both increased morbidity and mortality for a variety of chronic diseases. Together, immunosenescence and inflamm-aging may increase susceptibility to infection and contribute to aged-related health conditions such as arthritis, equine Cushing’s disease, and laminitis. Nutritional immunology is a new field of study, in which nutrition is used as a modifiable factor in impacting immune function in particular to delay/reverse immunosenescence and to improve the aged resistance to infection.  Further, nutritional interventions are practical, cost-effective approaches to mitigating this age-related breakdown in immune function.  Natural dietary compounds found in a variety of plants, roots, fruits, vegetables, nuts and seeds are promising candidates in helping to combat the effects of an aging immune system. Several natural dietary compounds (carotenoids, flavonoids, isothiocyanates, terpenoids, proanthocyanidins, omega fatty acids, and polyphenolic compounds) have been shown to possess broad biological activities of anti-oxidative, anti-inflammatory, detoxification, regulating signaling pathway, modulation of enzyme activities, and improving immune responses to vaccination.  Unfortunately, few studies have been conducted to better understand what effect nutrition may have on modulating or improving immune responses of the aged horse.  Previous and current nutritional studies to improve immune function in old horses by supplementation with vitamin E, n-3 polyunsaturated fatty acids (DHA), prebiotic and polyphenols will be reviewed here.  More research is needed to identify effective and optimal conditions for various nutritional intervention regimens to improve the function of the aged immune system of the horse.

Keywords: horse, aging, immune