How old your dog REALLY is: Why multiplying ‘human years’ by seven is a myth – and the biological calculator that reveals your pup’s ‘true age’
If you want to calculate the age of your dog, multiply the number of years they have lived by seven.
It’s the old cliché – but is it true?
Unfortunately, it’s not that simple, experts say, firstly because it varies from breed to breed, but also because our canine companions age at a different rate than we do.
For example, it takes people 18 years to reach adulthood. But because dogs often go through puberty – or their teenage phase – at about six months, they are only puppies until about nine months at the latest.
So how else can we work out a dog’s ‘true age’? MailOnline takes a look – including how a biological calculator is just one of the alternatives to the 7:1 annual ratio.
How can we work out a dog’s ‘true age’? MailOnline takes a look – including how a biological calculator is just one of the alternatives to the 7:1 annual ratio. A new formula has been created by researchers at the University of California (pictured) and is based on the rate at which molecules are added to DNA as we age
Variable: Part of the problem with trying to create a one-size-fits-all approach to a dog’s age is that it often varies depending on the breed, size and gender of the dog (stock image)
This new formula was created by researchers at the University of California and is based on the rate at which molecules are added to DNA as we age.
These molecules are known as methyl groups, which can change functions and are known as ‘epigenetic’ changes.
The scientists looked at these changes in the nucleic acid (called methylomes) of 104 labradors and compared them with those of humans.
They found that although the relationship was not linear, there were similarities in the timing of major milestones between dogs and us.
This was particularly strong when comparing similarly aged dogs and humans.
However, as discussed above, the team found that there were periods in the lives of dogs where the clocks did not match humans, including during puberty as they mature earlier in their life cycle than humans.
The research nevertheless allowed them to create a ‘biological calculator’ to determine a dog’s ‘true age’.
To determine this human equivalent, the formula involves taking the log of that age, multiplying it by 16 and then adding 31.
On this basis, an 18 year old dog would be 77 and a 2 year old dog 42 in ‘human years’.
Try our calculator above to see how old your dog is in comparison.
Of course, part of the problem with trying to create a one-size-fits-all approach to a dog’s age is that it often varies depending on the breed, size and gender of the dog.
For example, female dogs live slightly longer than male dogs, while small dogs have life spans that are considerably longer than those that are larger.
One study estimates that small dogs live an average of 16.2 human years, compared to 12 years for large dogs. Mixed breed dogs also tend to live a bit longer than pedigree dogs, meanwhile.
However, if we look at dogs as a whole, the average life expectancy is around 12.69 years.
That’s according to a recent study of nearly two million dogs who are clients of more than 1,000 vet clinics in the US.
How different dogs compare: Small dogs have significantly longer life spans than larger ones. However, in general, a dog’s life expectancy averages about 12.69 years
This chart shows how a dog’s behavior changes as it ages. Green shows how the brain develops and then begins to decline in senior years; orange shows how some traits, such as cognitive decline, increase exponentially in a dog’s geriatric years; red shows the slow decline in a dog’s activity and alertness
Separate research has also revealed how dogs become teenagers at just six months old, full-fledged adults at two and ‘seniors’ at around seven.
“Dogs mature faster than we do,” said lead study author Dr Naomi Harvey, a research manager at Dogs Trust and an academic at the University of Nottingham.
Disputing the 7:1 year cliché, she added: ‘Many one-year-old dogs have reached their full height and most will have gone through puberty or are nearing the end of it, so they are certainly not the equivalent of a seven-year-old. child!’
Her findings show that a one-year-old dog is a juvenile who has just completed puberty, and is similar to a 15-year-old human.
But just 12 months later, at two years old, dogs reached full maturity in the same way as a 25-year-old person.
Dr. Harvey found that dogs can be considered to enter their senior years at age seven and are considered geriatric at age 12 and older.
The former is defined as when the animal is older but healthy, and the latter is when ill health and death become likely.
A dog’s life: University of California researchers have claimed that dogs are middle-aged by the time they are two (stock photo)
The research shows that aging is defined by various behavioral and cognitive characteristics and tendencies.
For example, a dog’s brain continues to develop until it’s around seven, after which its attention span declines, accusing it of being a senior pooch now.
Geriatric dogs of 12 may show signs of being in a little more pain and may also suffer memory problems, similar to people with dementia.
So just how can you help your dog live longer? Well, keep an eye on his weight for a start.
One study found that a normal weight Labrador lives 13.6 years as a female and 13.3 years as a male, but if overweight, that drops to 13.0 and 12.7 respectively.
Meanwhile, a normal weight Yorkshire Terrier lives 15.5 years (female) or 16.2 (male), but this drops to 13.5 or 13.7, respectively, if it is overweight.
Research has also suggested that it is better dental care can also help.
But if one thing is certain, it may not be the most accurate way to estimate your dog’s true age on the 7:1 year ratio.