How long do dogs live in human years?

Apr 22, 2022

The most known rule for calculating a dog’s age in human years is to multiply their age by 7. Where does this come from? Is it true?

There’s evidence of humans trying to calculate dog’s ages since the thirteenth century. An inscription on the Cosmati Pavement on Westminster Abbey, from year 1268, stated that a human year is equivalent to 9 dog years. Later on, in the 1950’s, the 7-year-rule became popular. It’s a simple logic rule, given the fact that back then the average lifespan for a human was around 70 years, and the average lifespan for a dog was around 10 years.

Truth is that the number of human years a dog has depends on many factors, such as the dog’s breed or size (normally, smaller dogs live longer than big ones), and it’s not 7 human years per dog year.

There are 5 life stages for dogs

Puppy: until 6 or 7 months old. It’s a life stage where dogs go through many physical and mental changes, so it’s important to give them food adequate for their age, to socialize them and train them.

Junior: between 7 months and a year and a half. In this phase dogs have reached sexual maturity but they are still growing physically.

Adult: between a year and half until ¾ of their lifespan. In this phase dogs have finished growing physically, and they are socially mature.

Senior: the last quarter of a dog’s lifespan. It’s a time when dogs sleep more, eat less and have more difficulties when it comes to exercising.

Geriatric: beyond their expected lifespan. During this phase it’s very important to visit the vet frequently, because their physical health is declining.

In 1953, scientist A. Lebeau did research on the topic of dog years in human years, and he published a study where he found the 7-year-rule to be false.

If this rule were true, it would imply that humans would be able to reproduce at age 7, and a big percentage of us would make it to 150 years old.

One of his findings was that dogs don’t age in the same way humans do, they age faster when they’re younger and slower when older.

Lebeau came to the conclusion that, in general, a one-year-old dog has the equivalent to 15 human years; a two-year-old dog, has the equivalent to 24 human years; and from then on, each dog year is equivalent to 4 human years, approximately.

Further studies noted that these data can vary greatly depending on the breed, size and weight of the dog. In general, dogs of bigger breeds and sizes reach maturity later in life, and they also reach old age before small dogs do.

Age signs in dogs

Many times, when we adopt a dog, we don’t know exactly how old they are. Vets can estimate a dog’s age based on different factors:
-Teeth: most dogs have a complete set of adult teeth by the time they are 4 months old. Normally, tartar accumulation can begin to be seen between 3 and 5 years old, and age can also be estimated based on how worn out the teeth are.
-Eyes: it is common for old dogs to get cloudy eyes due to cataracts.
-Hair: as they age, it is normal for dogs to show grey hair on different parts of their bodies.

Tips that will help your dog live longer

Even though we can’t help that dogs live a shorter life than humans, we can help them live a long and happy life by following some simple steps:

-Feeding them a healthy diet
A natural diet, that contains all the necessary nutrients for your best friend, will help them make it to old age in good condition.

-Taking them out for daily exercise
Daily exercise helps control weight, maintain cardiovascular health and a strong immune system.

-Keeping vaccines up to date
Vaccines will keep your dog away from diseases that can have an impact on their health.

-Going to regular vet check-ups
Visiting the vet frequently can help to detect health problems early and, in some cases, to avoid them in the first place.

To sum it up…

A dog’s age in human years isn’t equivalent to 7 human years per dog year, it actually depends on many factors such as breed or size, and it’s hard to define an exact ratio given the difference between species.

Everyone that has a dog at home would like to know their “human age” in order to understand in which life moment they are in and to adapt to their needs. Luckily, we have vets, and we can rely on them to understand our best friend’s needs, to know in which life stage they’re in and what we can do to keep the around being happy and healthy for the longest time possible.