Meeting Abstract
Small mammals typically have lower whole animal metabolic rates compared with large mammals. As a result, large mammals with higher whole animal metabolic rates have longer lifespans than small mammals. However, across domestic dog breeds (Canis lupus familiaris), we find that although small breed dogs tend to have lower whole animal metabolic rates than large breed dogs, they also tend to live longer, an opposite pattern to most mammals. We were interested in the cellular mechanism that may allow for small breed dogs to age slower compared with large breed dogs in the context of oxidative stress. Primary dermal fibroblasts were grown in tissue culture from domestic canine skin samples that were obtained from veterinarians. Dogs were grouped by age and breed size. We measured rates of RS (reactive species) production, reduced glutathione, mitochondrial content, basal and maximal rates of lipid peroxidation in primary fibroblasts from dogs. Our results show that large breed dogs have higher concentrations of reduced glutathione throughout their lives compared with small breed dogs. In general, mitochondrial content decreases as breeds of all sizes age, though, RS production show increases in older large breed dogs. We also see significant differences in maximal lipid peroxidation in large breed puppies, suggesting that cellular damage starts accruing at a young age. Thus, large breed dogs, with their higher whole animal metabolism and faster growth trajectories, also show an increased production of pro-oxidants and higher lipid peroxidation damage, thus, demarcating a potential mechanism for their decreased lifespan compared with small breed dogs.
