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A 13-year-old Cocker Spaniel in human years

Cocker Spaniel at 13 years
79human years
medium breed — senior, roughly 100% through a typical lifespan
AVMA size-based15 for year one, 9 for year two, then 5/year for a medium breed79human years
Epigenetic clock16 × ln(age) + 31 — Wang et al. 2020, calibrated on Labradors72human years
Difference between the twothey disagree — see the note below-7years
Life stagesenior
Size class20–30 lb — larger dogs age fastermedium
Typical lifespanmedian for medium breeds13years
Share of life so far100%
Typical years remaininga population median, not a prediction about your dog0years
Breed
Cocker Spaniel
Age
13 years

Two answers, and neither is simply wrong

79 human years by the AVMA size-based table: 15 for the first year, 9 for the second, then 5 a year for a medium breed.

72 human years by the epigenetic clock published in Cell Systems in 2020 — human age = 16 × ln(dog age) + 31, derived from DNA methylation.

They differ by 7 years here. The epigenetic clock is a measurement rather than a convention and captures early life remarkably well, but it was calibrated on Labradors and cannot see breed size. The AVMA table does account for size but is a smoothed consensus.

Bigger dogs age faster

This is backwards from mammals in general, and it is why no single conversion works. A medium breed adds about 5 human years per dog year after the second birthday; a small breed adds 4, a giant breed 6.5.

The old "multiply by seven" rule gets a one-year-old badly wrong in one direction and a fifteen-year-old badly wrong in the other.

Where this dog is

Life stage: senior. Roughly 100% through a typical lifespan for a medium breed, with a median of 13 years.

Those are population medians from veterinary data, not a forecast — individual dogs of every size routinely live well past them.

The one thing that moves the number

Weight. A landmark Purina lifetime study found dogs kept lean lived about 1.8 years longer than littermates fed 25% more. That is a larger effect than almost anything else within your control.

Notes

  • Bigger dogs age faster, which is backwards from mammals in general and is the reason no single conversion table works. A medium breed adds about 5 human years per dog year after the second birthday; a small breed adds 4, a giant breed 6.5. The old "multiply by seven" rule gets a one-year-old badly wrong in one direction and a fifteen-year-old badly wrong in the other.
  • The two methods differ by 7 years at this age, and neither is simply wrong. The epigenetic clock is measured from DNA methylation and captures early life very well, but it was calibrated on Labradors and cannot see breed size. The AVMA table does account for size but is a smoothed consensus rather than a measurement.
  • At senior stage, twice-yearly vet visits are the standard recommendation rather than annual ones. Most of what shortens a senior dog's remaining time — dental disease, arthritis, kidney and heart changes — is manageable when found early and expensive when found late.
  • Lifespan figures are population medians from veterinary data, not a forecast. Individual dogs of every size routinely live well past them.

Nearby sizes