Aging is modifiable: current perspectives on healthy aging in companion dogs and cats

Aging is a universal, continuous, and complex process in which an animal's biological ability to resist, react to, and recover from environmental stressors declines and there is an alteration of physiological processes in response to accumulating cellular damage. In companion dogs and cats, aging is often perceived as an unmodifiable decline in physical and mental capabilities combined with increased morbidity, all aligned with chronological age. An insufficient understanding of healthy aging means missed opportunities to alter the trajectory of health span and maintain overall quality of life despite those changes that are inevitable. We believe that the course of aging is modifiable throughout an individual's entire life, with healthy, or successful, aging being an achievable goal. We explored herein 3 aspects of healthy aging: the need for a better scientific understanding of aging processes in dogs and cats and practical potential of biological aging clocks; a meaningful definition of healthy aging; and greater use of validated clinical monitoring tools and resources. A universal, meaningful, and actionable definition of healthy aging is needed to dissociate aging from declining health and poor quality of life in all their manifestations. The unique relationship between pets and their caregivers may demand a more expansive definition than that for humans. We propose that healthy aging in dogs and cats should be regarded as aging in which the individual maintains functional capabilities and develops resilience sufficient to meet their own physical, behavioral, social, and emotional needs throughout all adult life stages, while sustaining the human-animal bond.