As a veterinarian I am often asked “What age is my dog compared to human years?” This is especially relevant as dogs age or become “senior pets.” Dogs will age by several factors, but breed (or size) is the most important factor. Giant breed dogs age faster than small breed dogs for example. Other factors (just as with humans) can affect aging, such as: body weight, general health, exposure to toxins or high risk factors, diet and genetic predisposition.
The important age categories or changes are when a pet leaves childhood to become an adult and when a pet becomes a senior.
Dog Age Categories
- Infancy will last only a few weeks, until about 6-8 weeks of age.
- Childhood will last from 2 months until approximately 4 months for small breeds and 2-9 months for large breed dogs.
- Teen years again will also vary by breed, with small dogs lasting from 4-9 months of age and large breeds typically from 9-18 months old.
- Adulthood starts at 9-12 months for small breeds and 18-24 months for large breeds.
- Senior years can start as early as 7 for giant breeds and not until age 11-12 for smaller breed dogs.
For example: a 9-year-old Great Dane is a senior citizen, while a Chihuahua would need to be 12-14 years old to be a senior given good health and proper nutrition.
The following chart will help to determine your dogs biological age to human years.