This document is the transparency reference for dogage.co. It describes what data powers the site's calculators and breed pages, where that data comes from, which formulas run, how life stages are defined, and the editorial standards that govern every piece of content. It is written for readers who want to verify a number or check a source before acting on it — whether they are a dog owner, a veterinary professional, or a researcher auditing the site's claims.
What dogage.co calculates
The site's calculators and editorial content combine three categories of output:
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Age translation. Converting a dog's chronological age into a human-equivalent biological age. Four formulas are reported in parallel on the calculator: seven-year rule (reference), AVMA size-adjusted, UCSD epigenetic clock, and breed-median percentile. Each answers a slightly different question; the combined output is more informative than any single formula.
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Life-stage classification. Placing the dog into one of six stages (puppy, junior, adult, mature, senior, geriatric) based on size-adjusted thresholds. This is what drives the site's care-framing content — wellness-exam cadence, screening priorities, nutrition stage, and so on.
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Lifespan estimation. Returning the expected remaining-lifespan range based on breed-specific observational data plus size and life-stage context.
None of these are diagnostic tools. They provide population-level reference information for owner decision-making and for conversations with a veterinarian. Specific clinical decisions belong with a veterinarian who knows the specific dog.
Breed data sources
dogage.co's 200-breed manifest draws from two primary source categories:
Morphology, temperament, and breed description come from the American Kennel Club breed-standards database[11]. AKC provides authoritative breed-group classification, weight and height ranges, coat type, origin, and standardized temperament descriptions. Similar data from the UK Kennel Club and FCI is reviewed when AKC classifications diverge from international standards.
Lifespan and breed-specific mortality come primarily from the UK Royal Veterinary College's VetCompass programme, via McMillan et al. (2024)[2]. The McMillan study analyzed 584,734 UK companion dogs across 155 breeds, reporting observational median lifespans from general-practice veterinary records. For the 15 non-AKC designer breeds in the manifest and the ~45 AKC breeds with insufficient RVC coverage (fewer than 100 dogs in the dataset), lifespan is constructed from multi-source medians drawn from AKC breed-standard ranges, breed-club surveys where available, and relevant smaller peer-reviewed studies. Every breed page documents the specific source category used.
Breed-specific health data uses OFA (Orthopedic Foundation for Animals) statistical data for disease prevalence, CHIC recommendations for breed-specific screening, and breed-specific peer-reviewed epidemiology studies where available (e.g., Anderson et al. 2018 for osteoarthritis predispositions[12]).
Lifespan data — RVC versus AKC
The choice between RVC and AKC lifespan figures is deliberate and worth explaining.
AKC breed-standard lifespan ranges are drawn from breed-club surveys, historical breed-standard documents, and informal practitioner consensus. They represent what a healthy, well-bred, well-cared-for dog of the breed can live to — an aspirational upper bound. For many breeds the AKC-published range is 1-3 years higher than the observed RVC median.
RVC VetCompass medians are drawn from ~500,000+ UK companion dogs recorded through general-practice veterinary clinics. They represent what dogs of the breed actually live to under typical companion-dog care conditions — an observational median. The distribution includes dogs lost early to preventable causes and dogs who reach the far tail of the breed's distribution; the median sits in the middle.
Both are legitimate, and both answer valid questions. For the "how long should I expect my dog to live" question that drives life-stage care planning, RVC is the more defensible reference. For the "how long could my dog live with excellent care" question, AKC is a reasonable upper bound. dogage.co displays RVC medians as the primary lifespan number on breed pages, with AKC ranges shown when relevant.
Age translation formulas
Four formulas are implemented. All four run client-side in the dog age calculator and return their outputs in parallel.
Formula 1 — Seven-year rule. human_age = dog_age × 7. No biological basis; retained on the site for reference and because users expect to see it. Always displayed with contextual framing about why it's wrong.
Formula 2 — AVMA size-adjusted. A piecewise function: 15 human-years in the first dog-year, 9 more in the second, then 4/5/6/7 human-years per dog-year after age 2 for small/medium/large/giant breeds. Not derived from a single peer-reviewed paper; a practitioner-consensus formula aligned with AAHA 2019 life-stage guidelines[6] and calibrated to observed size-lifespan data[4].
Formula 3 — UCSD epigenetic clock. human_age = 16 × ln(dog_age) + 31. Derived by Wang et al. (2020) from DNA methylation data in 104 Labrador Retrievers and 320 humans[1], extending Horvath's 2013 human methylation clock to the canine domain[8]. The most rigorously derived dog-age translation published to date. Covered in depth in the UCSD epigenetic clock explained.
Formula 4 — Breed lifespan percentile. percent_of_life = (dog_age / breed_median_lifespan) × 100. Places the dog in its own breed's lifespan distribution using McMillan 2024 medians[2]. Not a human-equivalent translation — a different answer to a different question ("how far along is this dog in breed-specific lifespan") that is more actionable for life-stage care planning than the human-year number.
The full worked-example walkthrough of all four formulas is in how to calculate dog years accurately.
Life-stage framework
dogage.co uses the Fortney 2012 size-adjusted life-stage thresholds[5] as the baseline, cross-referenced with the AAHA 2019 Canine Life Stage Guidelines[6] for care-protocol framing.
| Size category | Senior threshold | Geriatric threshold |
|---|---|---|
| Toy (under 10 lbs) | 9 years | 12 years |
| Small (10–20 lbs) | 8 years | 11 years |
| Medium (20–50 lbs) | 7 years | 10 years |
| Large (50–90 lbs) | 6 years | 9 years |
| Giant (over 90 lbs) | 5 years | 7 years |
These thresholds appear identically on every breed page's senior-care subsection and are consistent with the breed-median lifespan data the calculator uses — senior stage is defined as roughly the final 25% of expected breed-specific lifespan. The AAHA 2019 guidelines provide the structured care-protocol expectations at each transition (wellness-exam cadence, senior bloodwork, cognitive baseline assessment).
Editorial standards
All factual claims on dogage.co trace to one of the following source categories:
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Peer-reviewed research — the highest-priority source category. Primary journals include Nature / Scientific Reports, Cell and Cell Systems, Journal of Veterinary Internal Medicine, The American Naturalist, Veterinary Clinics of North America, The Veterinary Journal, Research in Veterinary Science, and similar.
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Veterinary organization guidelines — AAHA, AVMA, WSAVA, BSAVA, and equivalent. These are cited when they represent practitioner consensus on care protocols rather than primary research findings.
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Breed-standard authorities — AKC, UKC, FCI for breed morphology, classification, and standard descriptions. Used for breed identification, not for lifespan claims (which default to RVC observational data).
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Research consortiums — Dog Aging Project (University of Washington), Morris Animal Foundation (Golden Retriever Lifetime Study), AKC Canine Health Foundation. These are cited for specific findings they publish rather than as blanket authorities.
Commercial consumer-pet content aggregators — blog-style pet-care sites that compile information from other sources rather than conducting or directly reporting primary research — are never cited, including when individual articles on those sites are factually correct. The reasoning is E-E-A-T: citing aggregator content reduces topical authority rather than reinforcing it, because it signals to search engines and human readers that dogage.co is reiterating rather than sourcing. Where an aggregator article cites a peer-reviewed paper, dogage.co cites the peer-reviewed paper directly and bypasses the intermediary.
What dogage.co does not provide
The site's deliberate scope-limits matter as much as what it covers:
- No specific medication recommendations. Drug names, dosages, or treatment regimens are veterinary decisions, not calculator outputs.
- No specific supplement recommendations. Product categories (joint support, omega-3) may be referenced with explicit "veterinary consultation" framing. Specific brands or formulations are not recommended.
- No diagnostic claims. Condition names appear for observational framing (dental disease, cognitive dysfunction, osteoarthritis) but the site never asserts a specific dog has a condition.
- No end-of-life timing or method content. Quality-of-life assessment is deferred to veterinary conversation. Methods and timing are outside the site's scope.
- No individualized care plans. The site provides population-level reference data and life-stage frameworks. Specific care plans are built with a veterinarian.
- No breeder or purchase recommendations. The site is a reference resource, not a directory.
Across all YMYL-adjacent topics (senior care, nutrition, mortality, age-related conditions), the only specific action the site recommends is veterinary consultation. <MedicalDisclaimer /> appears on every YMYL page directly after the introduction.
Maintenance and updates
Breed lifespan data is refreshed when new RVC VetCompass publications appear — typically annually, though the cadence varies. The most recent comprehensive source is McMillan et al. (2024)[2]. When new publications appear, affected breed pages are updated and the source citation refreshed.
Formula implementations have been stable since Wang et al. (2020)[1] and are unlikely to change without a peer-reviewed successor to the UCSD epigenetic clock. Any future formula update will be documented on this page and in a changelog entry.
Editorial content is reviewed on a rolling basis. Articles track publishedAt and updatedAt timestamps in their frontmatter; readers can see when a piece was last reviewed. Structural methodology changes (source policy, formula changes, life-stage threshold revisions) are documented in the site's BLUEPRINT file and surfaced through the changelog.
Where to verify
For any specific claim, the corresponding source is in the article or breed page's Sources list. All citations link to the canonical paper URL or organizational source. For the full set of primary sources across the site, see the sources page. For the calculator's formula details, see how to calculate dog years accurately. For the underlying biology of the UCSD formula, see the UCSD epigenetic clock explained. For the research landscape on breed-specific aging, see breed-specific aging research.
dogage.co's commitment is to be traceable. If a number appears on the site and you want to verify it, the source should be one click away. If that ever fails, the number should be treated as in-review rather than in-evidence.
