In a controlled cross-sectional cohort of 80 intact Beagles aged 1–11 years, immune aging proved heterogeneous and non-linear: absolute leukocyte counts declined with age before rebounding in geriatric animals, while serum cytokines showed sex-stratified trajectories — more cytokines varied significantly with age in males than females, though age-by-sex interaction effects did not survive false discovery rate correction. A 90-day intervention trial in 24 young Beagles then compared rapamycin, canagliflozin (an SGLT2 inhibitor), and dietary restriction. Rapamycin produced the broadest cytokine response profile; canagliflozin showed narrower immune changes alongside modest body-weight reduction; dietary restriction reduced weight without detectable immune endpoint changes.
This is genuinely useful translational groundwork. Dogs share human environments, develop spontaneous age-related disease, and age roughly seven times faster — making them more informative surrogates than rodents for geroscience. The finding that rapamycin moves the widest array of immune endpoints in just 90 days aligns with its established mechanistic breadth via mTORC1 inhibition and echoes longevity data from the Dog Aging Project. Canagliflozin's immune-modulating signal is intriguing given accumulating cardiovascular outcome data in humans. However, the intervention arms are critically small (roughly 6 animals each), measurements are endpoint-only without baseline, and causality cannot be established. These results are squarely hypothesis-generating — they justify larger, longitudinal, placebo-controlled dog trials but should not yet inform human supplementation decisions.