page_title: Aging in dogs
section_title: Terminology
hierarchical_section_title: Aging in dogs / Terminology
caption_attribution_description: English: Cairn Terrier named Charlie on bed being pensive
context_page_description: Aging in dogs varies from breed to breed, and affects the dog's health and physical ability.
  As with humans, advanced years often bring changes in a dog's ability to hear, see and move about easily. Skin condition, appetite and energy levels often degrade with geriatric age, and medical conditions such as cancer, kidney failure, arthritis, dementia, and joint conditions, and other signs of old age may appear.
  The changes in care often required by an older dog may lead a non-experienced owner to release the animal to a shelter or rescue organization. Non-profit groups have sprung up in response to the growing need for senior dog rescue.
  The aging profile of dogs varies according to their adult size: smaller dogs often live over 15–16 years, medium and large size dogs typically 10 to 13 years, and some giant dog breeds such as mastiffs, often only 7 to 8 years. The latter reach maturity at a slightly older age than smaller breeds—giant breeds becoming adult around two years old compared to the norm of around 13–15 months for other breeds.
context_section_description: The terms "dog years" and "human years" are frequently used when describing the age of a dog. However, there are two diametrically opposed ways in which the terms are defined:
  One common nomenclature uses "human years" to represent a strict calendar basis (365 days) and a "dog year" to be the equivalent portion of a dog's lifetime, as a calendar year would be for a human being. Under this system, a 6-year-old dog would be described as having an age of 6 human years or 40–50 (depending on the breed) dog years.
  The other common system defines "dog years" to be the actual calendar years (365 days each) of a dog's life, and "human years" to be the equivalent age of a human being. By this terminology, the age of a 6-year-old dog is described as 6 dog years or 40–50 human years, a reversal from the previous definition.
  However, regardless of which set of terminology is used, the relationship between dog years and human years is not linear, as the following section explains.
caption: A small dog breed aged 13 human years, such as this Cairn Terrier, would be approximately 68 years old in dog years, while a large breed would be 96.
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