How to Estimate the Age of Dogs in Human Years
Veterinary & Aquatic Services Department, Drs. Foster & Smith

Q. How do I determine how old my dog is?
 
A.

Determining the age of a dog

Except in young dogs, determining the age of a dog is an 'educated guess,' at best.

The age of puppies less than 7 months of age can be determined by which temporary and permanent teeth are present.

Using radiographs (x-rays), the presence or absence of growth areas of the bones in young dogs (up to about one year of age) can help determine age. Radiographs are rarely taken for this purpose, however.

In older dogs, age is generally estimated by the wear on the teeth. Unfortunately, this can be influenced by the size and breed of the dog, the dog's diet and chewing habits, the shape and positioning of the jaws, and the amount of dental care the dog has received.

Graying of the hair is not a good indication of age – some animals begin to gray at 3 or 4 years of age.

Dog years in human terms

The old adage that one 'dog' year equalled seven 'human' years was quite a generalization. The size of the dog plays a large role in determining the relative age of a dog in human years, as you can see from the table below. Those ages depicted in gray signify a 'senior' dog, while those in blue would be 'geriatric.' One must realize these are rather arbitrary classifications and not set in stone.

Adult Size in Pounds
Age 0-20 21-50 51-90 Over 90
6 40 42 45 49
7 44 47 50 56
8 48 51 55 64
9 52 56 61 71
10 56 60 66 78
11 60 65 72 86
12 64 69 77 93
13 68 74 82 101
14 72 78 88 108
15 76 83 93 115
16 80 87 99 123
17 84 92 104
'Senior'
'Geriatric'
18 88 96 109
19 92 101 115
20 96 105 120
Relative Age of Your Dog in Human Years

The oldest recorded age of a dog is 29 years old.

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Reprinted from PetEducation.com.