Ever wonder why some breeds of dogs live longer than others? Or why wild canids, such as gray wolves, live longer than similar sized domesticated dogs (20.6 vs 10-12 years)? Drs. Ana Jimenez (Colgate University, New York) and Dr. Cynthia Downs (State University of New York, Syracuse) teamed up to examine a common marker of aging in animals – oxidative stress. Oxidative stress happens when there is a build-up of free radicals in the body. These are highly reactive molecules that have unpaired electrons, meaning they can interact with other molecules and cause damage to tissues in the body. In general, animals that have higher metabolisms tends to make more free radicals and thus tend to have shorter lifespans. The oxidative stress theory of aging describes how animals that produce more free radicals, or have less antioxidants to break them down, live shorter lives than those that develop less oxidative stress.
In a new study published in the American Journal of Physiology – Regulatory, Integrative and Comparative Physiology, Drs. Jimenez and Downs measured markers of oxidative stress and antioxidants in blood samples collected from domestic dogs with the help of veterinarians and wild canids housed at zoos. Consistent with the oxidative stress theory of aging, domestic dogs develop more cellular damage with aging. In contrast, wild canids have more antioxidants as they age. These findings may help explain why wolves have longer potential lifespans than domestic dogs.
In addition, larger wild canids have higher levels of antioxidants than smaller animals, a pattern not replicated in domestic dogs. In fact, smaller domestic dogs have more oxidative stress and less antioxidants than larger domestic dogs – a pattern that does not match their longer lifespans.
AG Jimenez, CJ Downs. Untangling life span and body mass discrepancies in canids: phylogenetic comparison of oxidative stress in blood from domestic dogs and wild canids. American Journal of Physiology – Regulatory, Integrative and Comparative Physiology. 319(2): R203-R210, 2020. https://doi.org/10.1152/ajpregu.00067.2020