Many dog owners wonder how old their dog is in relationship to the human aging process. While this is not technically correct, it is a fun sort of thing for owners to do when considering their dogs lifespan.

The old standard use to be that for every year of age the dog was you could multiply by 7 to get its “human” age. This standard is no longer held to be true. We can see many dogs live more than 10 years, but 10 years would be the equivalent of 70 in human years, so although the math is simpler we should disregard this old standard.

Dog owners should also realize some dog breeds age faster than others. The large, and giant, dog breeds tend to have shorter lifespans but mature slower than small dogs.

Aging a Small to Medium Sized Dog

The first year is 10 years, the second year is 10 years, after that each year is 4 years.

As such a small or medium sized dog who is 10 years old in dog years, would be 10+10+(8 x 4) or 52 years in human years.

Please note for teacup dogs, due to health problems associated with being so small, the expected lifespan is much shorter than that of a healthy toy sized dog.

Aging a Large Dog

The first year is 10 years, the second year is 10 years, after that each year is 5 years.

As such a large sized dog who is 10 years old in dog years would be 10+10+(8x5) or 60 years in human years.

Aging a Giant Dog

The first year is 10 years, the second year is 9 years, after that each year is 6 years.

As such a giant breed dog who is 10 years old in dog years would be 10+9+(8x6) or 67 years in human years.

Factors that Determine Lifespan of Dogs

Of course there are other factors that determine the lifespan of a dog, it is not always old age that kills them. The giant breeds of dogs, the Great Dane, for example, often have health problems which shorten their lifespan.

Right from the start there are factors that will affect how long a dog will live, certain breeds have more health problems. Breeders who do not invest any time, or money, proving their dogs are genetically sound often breed low quality pups, some with genetic health problems, such as heart deformities. Some breeders intentionally underfeed their pups to keep them small, or select abnormally small dogs and breed them, to sell as “teacup” puppies, many of whom have health problems that shorten their lifespan.

Purebred dogs, and especially inbred dogs, tend to have more health problems. Mutts tend to have something called “hybrid vigor” often giving them fewer health problems, and longer lives.

The dog food you select for your dog can impact its lifespan, although you may not think so at the time. Some dog foods use lots of low quality filler, and dangerous chemicals, cheap preservatives (BHT, BHA, and Ethoyquin). All these things tend to add up to health problems later in life. As well because the dog's body has been working hard digesting poor quality ingredients, other health concerns may arise. Cancer is a leading killer of pets and is often linked to ingredients in pet food.

Obesity, and diabetes, are both common in dogs, and can be the result of a low quality diet (you will note all dog foods tell you they are great, but the standards for dog food quality are not particularly high in some countries including the USA).

Proper veterinarian care, such as vaccinations, and spaying, or neutering, can also prolong a dog's expected lifespan. Regular check ups can spot problems before they become life threatening.