Mortality

The typical lifespan of dogs varies widely among breeds, but for most the median longevity, the age at which half the dogs in a population have died and half are still alive, ranges from 10 to 13 years.[132][133][134][135] Individual dogs may live well beyond the median of their breed. The breed with the shortest lifespan (among breeds for which there is a questionnaire survey with a reasonable sample size) is the Dogue de Bordeaux, with a median longevity of about 5.2 years, but several breeds, including Miniature Bull Terriers, Bloodhounds, and Irish Wolfhounds are nearly as short-lived, with median longevities of 6 to 7 years.[135] The longest-lived breeds, including Toy Poodles, Japanese Spitz, Border Terriers, and Tibetan Spaniels, have median longevities of 14 to 15 years.[135] The median longevity of mixed-breed dogs, taken as an average of all sizes, is one or more years longer than that of purebred dogs when all breeds are averaged.[133][134][135][136] The dog widely reported to be the longest-lived is "Bluey", who died in 1939 and was claimed to be 29.5 years old at the time of his death; however, the Bluey record is anecdotal and unverified.[137] On 5 December 2011, Pusuke, the world's oldest living dog recognized by Guinness Book of World Records, died aged 26 years and 9 months. Aging in dogs covers the impact of aging in the domestic dog (Canis lupus familiaris), common medical and clinical issues arising, and life expectancy. Older dogs, like this 10-year-old Neapolitan Mastiff, often grow grey hairs on their muzzles; some dogs go grey all over. 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, renal failure, arthritis 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 such as Old Dog Haven have sprung up in response to the growing need for senior dog rescue. The aging profile of dogs varies according to their adult size (often determined by their breed): smaller dogs often live over 1516 years, medium and arge size dogs typically 10 to 13 years, and some giant dog breeds such as mastiffs, often only 7 to 8 years. The latter also mature slightly older than smaller breeds - giant breeds becoming adult around two years old compared to the norm of around 1215 months for other breeds. 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.[1] Under this system, a 6-year-old dog would be described as having an age of 6 human years or 4050 (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.[2] By this terminology, the age of a 6-year-old dog is described as 6 dog years or 4050 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. Life expectancy usually varies within a range. For example, a Beagle (average life expectancy 13.3 years) usually lives to around 1215 years, and a Scottish Terrier (average life expectancy 12 years) usually lives to around 1016 years. The two longest living dogs on record, "Bluey" and "Chilla", were Australian Cattle Dogs.[7] This has prompted a study of the longevity of the Australian Cattle Dog to examine if the breed might have exceptional longevity. The 100-dog survey yielded a mean longevity of 13.41 years with a standard deviation of 2.36 years.[8] The study concluded that while Australian Cattle Dogs are a healthy breed and do live on average almost a year longer than most dogs of other breeds in the same weight class, record ages such as Bluey's or Chilla's should be regarded as uncharacteristic exceptions rather than as indicators of common exceptional longevity for the entire breed.[8] A random-bred dog (also known as a mongrel or a mutt) has an average life expectancy of 13.2 years in the Western world.