Relative Age of Dogs in Human Years

The Aging Rate of Dogs

Everyone has heard the myth about 'dog years,' which often is described to mean that a dog ages the equivalent of 7 human years for every year of a dog's life. This would mean that a 3-year-old dog's age is equivalent to that of a 21-year-old person and a 4-year-old dog's age would be equivalent to that of a 28-year-old person...and so on.

The truth is, the relationship is more complex than that. Dogs of different breed sizes age at different rates and dogs age faster or slower depending on how old they are, as shown in the chart below.

Why Does It Matter?

There are a number of reasons why owners should be aware of this variable aging rate. Among the most important are: Puppies are going through their fastest growth for their first year or even two years. During that entire time, puppies should be fed a complete and balanced puppy food. It may seem strange to call an 18-month-old, 60-pound large breed dog a 'puppy' - but that's what he is.

Large breed puppies have unique nutritional needs. These needs include the need to manage caloric intake to help a large breed puppy achieve an ideal body condition. Keeping your large breed puppy lean helps keep muscular and skeletal growth rates at an ideal pace.

The rule of thumb is that dogs of breeds that typically weigh 50 pounds or more full grown are large breeds and will be puppies for 2 full years. In terms of selecting food and providing health care, you should treat them as puppies for that time.

Even though large breed dogs take longer to reach full maturity, they also will show signs of growing older sooner than other dogs. Very large dogs can become canine senior citizens as early as 5 years. Owners should treat their dogs accordingly.

Relative Age of Dogs in Human Years
Pet's Age 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Mature Weight
0-20 lbs 15 23 28 32 36 40 44 48 52 56 60 64 68 72 76 80 84 88 92 96
21-50 lbs 15 24 29 34 38 42 47 51 56 60 65 69 74 78 83 87 92 96 101 105
51-90 lbs 14 22 29 34 40 45 50 55 61 66 72 77 82 88 93 99 104 109 115 120
over 90 lbs 12 20 28 35 42 49 56 64 71 78 86 93 101 108 115 123
Growth
Senior

Table from Purina - The Aging Rate of Dogs

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