How old is your dog, and how size and breed impact ageing
Dog age isn’t one-size-fits-all. This guide explains how size and breed change the pace of ageing, why the “7 dog years” idea falls apart, and what life stages often look like for small, medium, and large dogs. You’ll walk away with a clearer sense of where your dog likely sits today, and how to shift from “how old are they?” to “how are they ageing?” for more proactive care with your vet.
If you’ve ever been told your dog is “middle-aged” or “senior” and thought that doesn’t feel right, you’re probably onto something.
Dogs don’t all age the same way. A seven-year-old German Shepherd and a seven-year-old Toy Poodle may share a birthday, but biologically, they’re worlds apart.
Understanding how dogs age, and why size, breed, and biology matter, is a crucial step in moving from reactive care to genuinely preventative health.
Why dog ageing isn’t linear
For decades, dog age has been simplified into rules of thumb. The idea that one human year equals seven dog years. The assumption that all dogs enter “senior” life at the same time.
Modern research tells a very different story.
Studies examining lifespan, disease onset, and biological markers of ageing consistently show that size is one of the strongest predictors of how quickly dogs age. Larger dogs tend to age faster and develop age-related disease earlier, while smaller dogs often experience slower biological ageing and longer lifespans.
Breed genetics, body composition, and lifestyle then layer on top of that baseline.
In other words, ageing is personal.
When dogs typically enter different life stages
The ages below are estimates, not rules. They’re useful as a starting point, not a diagnosis.
Small breeds (generally under 10 kg)
- Puppyhood: up to ~12 months
- Adulthood: ~1 to 7 years
- Senior years: ~8+ years
Small dogs often mature quickly but age more slowly overall. Many remain metabolically resilient and mobile well into their teens.
Medium breeds (roughly 10 to 25 kg)
- Puppyhood: up to ~12 to 15 months
- Adulthood: ~1.5 to 6 years
- Senior years: ~7+ years
Medium-sized dogs sit somewhere in the middle, with ageing patterns that vary more noticeably by breed and lifestyle.
Large and giant breeds (over 25 kg)
- Puppyhood: up to ~18 to 24 months
- Adulthood: ~2 to 5 years
- Senior years: as early as ~6 years
Larger dogs take longer to mature but tend to age faster once adulthood is reached. Research has linked this accelerated ageing to factors like growth rate, oxidative stress, and metabolic demand.
This is why a six-year-old large breed dog may already benefit from senior-focused monitoring and support.
What the science tells us about canine ageing
Peer-reviewed research into canine ageing has expanded significantly over the past decade. Large population studies have shown that:
- Body size is inversely related to lifespan, with larger dogs living shorter lives on average
- Age-related diseases emerge earlier in larger breeds, particularly joint disease and some metabolic conditions
- Biological ageing markers, including inflammation and frailty, don’t align neatly with chronological age
Researchers studying canine longevity, including work in veterinary epidemiology and immunology, increasingly emphasise that age should be understood as a biological process, not a calendar milestone. This aligns with perspectives long advocated by experts such as Dr Jean Dodds, who has highlighted the importance of individualised health decisions across a dog’s lifespan.
Why averages only get us so far
While size and breed provide useful context, they’re still population averages.
Two dogs of the same breed and age can have very different biological realities based on:
- Body condition and muscle mass
- Dental and inflammatory health
- Environment and chemical exposure
- Activity levels and mental stimulation
- Genetics and early-life nutrition
This is why some dogs feel “old” early, while others stay bright, mobile, and engaged well beyond expectations.
Age alone doesn’t tell the full story. Trends do.
From “how old is my dog?” to “how is my dog ageing?”
This is where modern preventative care is shifting.
Instead of asking how old is my dog supposed to be, the more powerful question becomes:
- How is my dog ageing right now?
- Are things stable, improving, or subtly changing?
- What can I support earlier, rather than react to later?
Answering those questions requires more than a birthday. It requires context, history, and data over time.
Bringing it back to the Life-Stage Blueprint
Life stages are not fixed boxes. They’re overlapping phases that change at different speeds for different dogs.
The Elita Blueprint is designed to reflect that reality. Rather than assigning your dog to a generic category, it brings together health records, environment, monitoring, and emerging biological insights to help you understand your dog’s ageing trajectory.
Not based on averages. Based on them.
If you want a clearer picture of where your dog truly sits, and what support makes sense now, Blueprint is where those pieces come together.
👉 Ready to understand how your dog is really ageing?
Explore Elita Blueprint and start building a personalised view of your dog’s health over time.