Equine Frailty as Indicator of Healthspan and Lifespan

Advancing age significantly increases the risk of chronic disease and functional decline in humans and horses. However, age alone is neither a sensitive nor specific predictor of morbidity due to wide inter-individual variability in the aging process. Instead, frailty—a multidimensional syndrome marked by declining physiological resilience and increased vulnerability to adverse outcomes—offers a more precise metric for assessing biological aging. Early identification of frailty enables veterinarians to detect underlying comorbidities driving functional decline, stratify risks for negative health outcomes, and implement targeted interventions that may delay, mitigate, or reverse its progression. These actions could extend horses' healthspan and improve their quality of life. In human medicine, validated frailty assessment models such as the frailty phenotype and cumulative deficit index provide robust tools for identifying frailty and predicting health outcomes. However, comparable methods are lacking in equine medicine, leaving veterinarians to rely on less objective indicators like chronological age or subjective judgments of quality of life. Developing a validated frailty instrument tailored for horses would enable better identification of frailty-related conditions, such as mobility impairments or chronic pain, while supporting more informed clinical decision-making and personalized care plans. Additionally, frailty screening would provide veterinarians and owners with essential tools to counter assumptions of poor prognosis based solely on age, a critical consideration in decisions regarding humane euthanasia. Screening for frailty in horses also opens opportunities for targeted interventions, similar to human gerontology, such as improving nutrition, optimizing musculoskeletal health through tailored activity programs, and treating reversible underlying diseases. Moreover, understanding the factors associated with frailty—ranging from biological markers and physical attributes to psychosocial elements like behavioral changes—requires longitudinal studies that focus on the aging equine population. This research will advance veterinary gerontology by identifying actionable risk factors, facilitating early intervention, and ultimately improving management strategies for older horses.