Background: Age-related changes in body composition, specifically a loss of lean mass and gain in fat mass, have been associated with negative health effects in dogs and cats. This retrospective study aimed to establish a baseline for how body composition changes with age and lifestage.
Hypothesis/
Objectives: To use body composition data from dual-energy X-ray absorptiometry (DEXA) scans to characterize changes in lean, fat, and total body mass with age in dogs and cats.
Animals: 7088 observations from 1331 colony-housed dogs and 6635 observations from 1111 colony-housed cats.
Methods: Historical DEXA data from 2006-2023 were analyzed using a linear model with orthogonal contrasts to determine the relationship between age and lean, fat, and total mass.
Results: Age had a significant effect on all body composition measures in both dogs and cats (P<0.001). In dogs, lean mass peaked at age 5 and generally decreased from age 5 onward, while fat mass on average increased until age 12 before declining. In cats, lean mass peaked at age 5 and generally decreased from age 5 onward, while fat mass on average increased until age 8 and generally decreased from age 8 onward.
Conclusions and clinical importance: By establishing a baseline of how lean, fat, and total body mass differ with age in dogs and cats, veterinarians may use these data to better assess body composition in patients, prepare for age-related changes such as sarcopenia and obesity, which may begin earlier than currently expected, and measure the impact of preventative interventions.
