Laurie's Blogs.

Firstly, have you heard of the Canine Frailty Index?  Have you used the Canine Frailty Index?  This sounds like a handy clinical tool… maybe it’s common sense, but I think it’s good to periodically quantify & qualify common sense… just to prove that it was it was indeed good sense all along!!  So, let’s dive into it!

Frailty, a clinical measure of aging’s impact on health, is gaining attention in veterinary medicine as a way to evaluate senior dogs’ vulnerability to adverse health outcomes like disability, disease, and death. In a recent article in Companion Animal (October 2025), Dr. Brennen McKenzie explores how frailty can be quantified in dogs using two main tools: the frailty phenotype and the frailty index, both adapted from human geriatrics.

Frailty Phenotype

The frailty phenotype categorizes dogs as normal, pre-frail, or frail based on five criteria: weight loss, exhaustion, slow gait, weak grip, and low energy. Studies, such as Hua et al. (2016) and Lemaréchal et al. (2023), have adapted this for dogs, using owner reports, clinical exams, and challenge tests like timed walking or strength assessments. These studies show frailty prevalence in dogs ranging from 8.6% to 41.9%, with frail dogs having significantly shorter survival times (e.g., 10.5 months for frail vs. 42.5 months for non-frail dogs). Frailty is linked to mortality risk, with factors like age and breed sometimes influencing outcomes, though sex differences are inconsistent.

Frailty Index

The frailty index uses a deficit accumulation approach, assessing 30+ variables (e.g., disease diagnoses, physical exam findings, lab abnormalities) to generate a continuous frailty score. Research by Banzato et al. (2019) and Chen et al. (2023) shows that frailty scores in dogs increase with age and correlate with mortality risk and lower health-related quality of life. A study on long-lived Rottweilers reported higher frailty scores (0.43 vs. 0.14 in mixed-age populations), underscoring the tool’s utility in assessing extreme aging.

Clinical Applications

Frailty assessment offers practical benefits for veterinarians:

•  Risk Stratification: Quantifying frailty helps predict outcomes for treatments like surgery or chemotherapy, aiding decision-making.

•  Early Detection: Higher frailty scores may prompt more intensive diagnostic screening for occult diseases.

•  Therapeutic Potential: In humans, interventions like diet and exercise can reverse frailty, and similar studies are underway in dogs.

•  Research Tool: Frailty serves as a proxy for biological age, accelerating research into therapies to extend healthspan and lifespan.

Practical Tools

The canine frailty index, in particular, is easy to integrate into senior wellness visits, as it uses data routinely collected during exams. A modified version is available at Loyal’s website, though it awaits independent validation.

Conclusion

Frailty assessment in senior dogs provides veterinarians with a robust tool to evaluate biological aging, stratify risks, and guide clinical decisions. While current evidence focuses on mortality prediction, ongoing research may expand its role in preventive care and treatment, offering hope for improving the health and longevity of aging canine patients.

Source: McKenzie, B. (2025). Assessing frailty in senior dogs. Companion Animal, 30(10), 2-5. https://doi.org/10.12968/coan.2025.0004 

Canine Frailty Index:  https://loyal.com/downloads/Loyal-Canine-Frailty-Index-03042025.pdf