Sarcopenia in Senior Dogs

Sarcopenia is the progressive loss of muscle mass and strength that occurs as dogs age. It reflects changes in how muscle tissue is built, maintained, and broken down over time, and tends to accelerate in the senior and geriatric years. The process is distinct from simple disuse—it involves shifts in metabolism, hormone signalling, inflammation, and the way the body responds to nutrition and activity. Owners often notice that an older dog feels lighter when lifted, moves more slowly on walks, or struggles with stairs or jumping into the car in ways that seem separate from obvious joint pain. Some dogs appear thinner over the hips and spine, or tire more quickly during familiar routines. These changes can develop gradually, and distinguishing age-related muscle loss from other conditions—such as underlying illness, pain-related inactivity, or appetite decline—requires careful observation. This page explores the signals that may suggest sarcopenia, the biological processes that drive muscle loss in older dogs, how the condition is assessed in practice, and the range of approaches that can be considered to support muscle health and function in the senior years.