There are many ongoing studies that look at the aging process, both in humans and horses. The aging process in the horse involves many changes in the immune system that may be related to genetics, nutrition, the environment, and any underlying disease condition that the horse may have.
Currently, geriatric horses are described as those over the age of 20 and exhibit “a decline in body condition, muscle tone, and general well-being.” The term “Inflamm-aging” has been used to describe the chronic low-grade inflammation that occurs along with aging, and these inflammatory markers can be used to predict morbidity (sickness) and mortality as those individuals with a high number of markers are more prone to disease. The question as to whether aging causes reduced immunity or whether reduced immunity causes aging has yet to be answered.
Researchers looked specifically at the age-related changes in the immune system focusing on the lungs. The lung “is faced with unique challenges because of its constant interaction with the external environment and thus may not share similarities to peripheral blood when considering age-related changes in immune function.” What the research determined is that inflamm-aging is not the same with respect to all of the horse’s organs and body systems and that the lungs “are unique in that they need to balance inflammation against the body’s demand for oxygen and carbon dioxide exchange.”
Learning more about the lung’s role both in airway function and immunity will not only help with the treatment of recurrent airway obstruction (RAO or “heaves”) in the geriatric horse but also asthma in our aging human population.
Scientific Article: Hansen, S , Baptiste KE, Fjeldborg J, Horohov DW “A review of the equine age-related changes in the immune system: Comparisons between human and equine aging, with focus on lung-specific immune-aging”. Ageing Res. Rev. 2015 Mar: 20:11-23. doi: 10.1016/j. arr.2014.12.002. Epub 2014 Dec 9.
Companion Article: Lesté-Lasserre, C “6 Senior Horse Studies to Know” theHorse, Sept. 2015, pp.16-20.