Dog Age In Human Years

Calculating Dog Years in to Human Years 

Original Article by Ray Chao for PetsBest

Everyone and their dog have heard the expression that “one human year equals seven dog years” when calculating the age of your pooch. But what exactly does that mean? And is it true? Well, it seems that it may simply be a tall “tail.” 

Although the origins of the seven-year theory is unknown, an inscription dating back to 1268 at Westminster Abbey in London, England, may be one source. According to the inscription, the lifespan of dogs is nine years compared to the 80-year lifespan of a human. While that is not quite the modern seven to one ratio, it may have started the obsession with calculating a dog’s age in human years. Luckily, since 1268, the lifespans for both dogs and humans have exceeded the calculations in Westminster Abbey.4   

By the 1950s, however, perhaps simply as a marketing strategy, the simple calculation of one human year equals seven dog years (the “seven-year rule”) gained world-wide acceptance and popularity with dog owners, veterinarians, dog food companies, and practically everyone, except maybe dogs, who probably don’t appreciate humans multiplying their age by seven. While this was a simple, convenient way to calculate a dog’s age in human years, veterinarians and scientists agree that it is simply not accurate. 

How Old is Your Dog in Human Years? 

When trying to correctly calculate a dog’s age in human years, it is important to remember that a dog’s size, breed and general health will also factor in to the equation. Fundamentally, dogs mature at a faster rate than humans (which is based on life expectancy). More specifically, however, when scientists study a dog’s developmental trajectory, they look at how a dog is aging on a molecular level because that is a more accurate way to calculate the aging process of any animal. In other words, all animals grow old and show similar signs of aging such as white hair, wrinkles and other age-related conditions. Researchers, however, have found that dogs age much more rapidly early in life, and then the aging process of dogs slows down significantly.3 

Dog Aging Cycle 

During their first year, a puppy matures rapidly at a rate significantly faster than a human baby. For example, during a puppy's first calendar year (equivalent to one human year), the puppy’s growth is similar to a human’s first 12-15 years of growth. So, a one-year-old puppy would be similar in age to a human teenager. After the puppy’s first year of accelerated growth, the difference between “dog years” and “human years” grows less and the rate of aging for dogs slows down. Therefore, a dog’s second calendar year is the equivalent of nine to ten human years, and each subsequent year is about the same as four to five human years.2 Also, the rate of aging will depend on breed and size, with small dogs having a longer life expectancy than larger dogs, so a six-year-old small dog under 20 pounds is about the same as 40 human-years old, but a six-year-old dog over 100 pounds would be 49 human-years old.4  Interestingly, like dogs, not all humans age at the same rate. Scientists have found that some people simply age at a faster rate than similar aged-peers. While it is not entirely clear why this happens, scientists believe early aging factors include genetics, stress, early trauma and lifestyle. 

Is it Important to Calculate a Dog’s Age in to Human Years? 

From a medical point of view, the study of the dog aging process is important to provide better medical treatment and overall health care to dogs. Moreover, this also allows researchers to compare species, which helps doctors treat humans, particularly with age-related diseases. Also, for pet owners, thinking of your dog’s age in terms of human years can help you better understand your dog’s life-cycle and health needs. For example, it is important to recognize when your dog becomes a senior dog because then you are more aware of possible health issues related to old age. Most dogs reach senior status between five and ten years old depending on size, breed and general health. So, by thinking of your five-year-old dog being the equivalent of a 65-year-old human may help you make necessary changes to diet, exercise, and pet health care. Of course, all dogs, particularly senior dogs, benefit from a specialized health care plan that ensures your dog receives any necessary health care. Pets Best can help you afford the best care possible for old or young pets with dog insurance plans customized to fit your needs and your budget.* 

Human Animal Bond 

Another reason people like to calculate a dog’s age as human years is simply to form a stronger connection to our dogs. Obviously, people can form very strong bonds with dogs, and there is a tendency to ascribe human characteristics and emotions to animals, which is called anthropomorphism. Scholars suggest, however, that many of these attributes we project onto our pets are not necessarily the pet’s reality, but simply a way for humans to feel closer to their pets. Interestingly, some researchers believe that humans engaged in anthropomorphic thinking as far back as 40,000 years ago as Paleolithic art represented humans in animal form and vice versa. Also, anthropomorphism may have allowed early humans to be more efficient hunters by predicting animal behavior. This in turn, according to researchers, helped the development of the modern human brain.1 

Ultimately, your dog’s age is simply a number; whether in dog years or human years. Most importantly, spend as much time with your dog, whether in dog time or human time. 


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