Plasma protein increase as a chronological aging factor in healthy toy poodles

Although extensive research has examined aging markers in larger dog breeds, little is known about small breeds. This study assesses the relevance of aging biomarkers examined in larger breeds and other biological species, focusing on toy poodles (N = 40) as a model of small breeds and retrievers (N = 17) serving as a large-sized reference. Healthy individuals with no significant health declines for up to a year post-data collection were studied for age-related changes in various parameters, excluding disease factors. Our cross-sectional analysis identified significant correlations between age and increases in plasma protein concentration and amylase levels across both breeds, with breed-specific age-related declines in vaccine responses to various viruses observed only in toy poodles. Longitudinal analysis over one year confirmed a significant temporal increase in plasma protein in toy poodles, with a similar, albeit non-significant, trend in retrievers. Unlike in other species, nicotinamide adenine dinucleotide levels and fecal microbiota showed no age-related changes. Additionally, the previously reported frailty index correlated with age in retrievers but not in toy poodles. Notably, including deceased individuals during the study strengthened correlations. These results suggest plasma protein increase as a chronological aging factor in toy poodles and enhance our understanding of aging in healthy small dog breeds.