How Old Is My Dog?

Click here for a similar article about cats.

Like humans, dogs don’t all age at the same rate. There are many factors that combine to determine the rate at which your dog ages and how long he will live. If you’re very lucky, you might have a dog like Bluey, who was the oldest dog ever according to the Guinness Book of Records. An Australian Cattle Dog, he died on November 14, 1939 at the age of 29 years, 6 months, and 12 days. Bluey is an extraordinary exception, however; as all dog owners know, the time we have with our dogs is generally much shorter.

The major factors that determine how long a dog will live are:

  • BREED AND/OR SIZE: Large breeds generally have a shorter life expectancy than smaller breeds, with small dogs living about half again as large dogs. See the chart at the end of this article for a comparison between small, medium, large, and extra large dog breeds. Even within a size range, some breeds tend to live longer than others. For example, Bluey’s breed, the Australian Cattle Dog, lives an average of one year longer than most other breeds in the same weight range. Many small and toy breeds live well into their late teens, while it’s unusual for a giant breed to live even 10 years.
  • CARE: It makes sense that dogs that are well cared for will most often live longer than those that are not. Quality of food, amount of exercise, good medical care, and healthy living conditions all contribute to a dog’s longevity.
  • GENDER: Human females tend to outlive human males, and this is also true with dogs. Depending on the breed and/or size, a female will usually live one or two years longer than a male.
  • NEUTERING: Un-neutered dogs are not generally as long lived as neutered ones. Neutering decreases the risk of cancer of the sex organs.
  • INDIVIDUALITY: Some people resist disease better than others, and the same is true of dogs. A dog with a strong constitution will generally outlive one that is weaker.

The old adage that one human year is equivalent to seven dog years is quite simply wrong. The longest-lived breeds will live twice as long as the shortest lived. And, the rate of aging of dogs is much different than humans, with dogs having a much shorter “childhood”. For example, a breed that has a life expectancy of 15 years is physically and sexually mature at one year, while equivalent human development takes 15 years. The same dog, at two years of age, is roughly equivalent to a human of 24. See the chart below for a more detailed look at dog to human age equivalency.

How old is your dog in human years